python3 -m pip install: warning and fatal error cffi on ARM Debian 9

### Step 1: Please describe your environment

* Operating system: Debian 9 Stretch for ARM, 32bit (soyoustart_com, ohv kernel)

### Step 2: Describe the problem:

The readme.md page says that following command should be used when installing zeronet on Linux:

sudo python3 -m pip install -r requirements.txt

and i ends in error on Debian 9 stretch ARM 32bit:

```
root@0:/home/ZeroNet-py3# sudo python3 -m pip install -r requirements.txt
Collecting gevent>=1.1.0 (from -r requirements.txt (line 1))
Downloading https://files.pythonhosted.org/packages/ed/27/6c49b70808f569b66ec7fac2e78f076e9b204db9cf5768740cff3d5a07ae/gevent-1.4.0.tar.gz (5.2MB)
100% |################################| 5.2MB 33kB/s
Ignoring cffi: markers 'sys_platform == "win32" and platform_python_implementation == "CPython"' don't match your environment
Collecting msgpack>=0.4.4 (from -r requirements.txt (line 2))
Downloading https://files.pythonhosted.org/packages/81/9c/0036c66234482044070836cc622266839e2412f8108849ab0bfdeaab8578/msgpack-0.6.1.tar.gz (118kB)
100% |################################| 122kB 1.1MB/s
Collecting base58 (from -r requirements.txt (line 3))
Downloading https://files.pythonhosted.org/packages/09/b2/21ac9591f055acc145afead895edeb73bbd69d95cf366fc5c2233f2434cb/base58-1.0.3-py3-none-any.whl
Collecting merkletools (from -r requirements.txt (line 4))
Downloading https://files.pythonhosted.org/packages/dc/b8/655f9be691387746957834fce8634a827497c62d306b09b557d2970a2672/merkletools-1.0.3.tar.gz
Collecting pyelliptic==1.5.6 (from -r requirements.txt (line 5))
Downloading https://files.pythonhosted.org/packages/e6/64/b235f8768dd37891acc924f724e7fd46921063da65e759f8123c6b0b42e9/pyelliptic-1.5.6.tar.gz
Collecting rsa (from -r requirements.txt (line 6))
Downloading https://files.pythonhosted.org/packages/02/e5/38518af393f7c214357079ce67a317307936896e961e35450b70fad2a9cf/rsa-4.0-py2.py3-none-any.whl
Collecting PySocks (from -r requirements.txt (line 7))
Downloading https://files.pythonhosted.org/packages/cd/18/102cc70347486e75235a29a6543f002cf758042189cb063ec25334993e36/PySocks-1.7.0-py3-none-any.whl
Requirement already satisfied: pyasn1 in /usr/lib/python3/dist-packages (from -r requirements.txt (line 8))
Collecting websocket_client (from -r requirements.txt (line 9))
Downloading https://files.pythonhosted.org/packages/29/19/44753eab1fdb50770ac69605527e8859468f3c0fd7dc5a76dd9c4dbd7906/websocket_client-0.56.0-py2.py3-none-any.whl (200kB)
100% |################################| 204kB 747kB/s
Collecting gevent-websocket (from -r requirements.txt (line 10))
Downloading https://files.pythonhosted.org/packages/7b/84/2dc373eb6493e00c884cc11e6c059ec97abae2678d42f06bf780570b0193/gevent_websocket-0.10.1-py3-none-any.whl
Collecting bencode.py (from -r requirements.txt (line 11))
Downloading https://files.pythonhosted.org/packages/98/d8/84d31b911a7cab865ec9070a982b9452b15db00373efcf1e4b4314a6a958/bencode.py-2.1.0-py2.py3-none-any.whl
Collecting coincurve (from -r requirements.txt (line 12))
Downloading https://files.pythonhosted.org/packages/4f/4b/c1c0aaa3a09d21e08de158f25e69134ea4b6563a8d5aee8d99e5f3e3447b/coincurve-12.0.0.tar.gz (948kB)
100% |################################| 952kB 166kB/s
Complete output from command python setup.py egg_info:
/usr/lib/python3.5/distutils/dist.py:261: **UserWarning**: Unknown distribution option: 'long_description_content_type'
warnings.warn(msg)
warning: no files found matching 'NOTICE'
warning: no files found matching 'requirements.txt'

Installed /tmp/pip-build-_3eshne2/coincurve/.eggs/requests-2.22.0-py3.5.egg
Searching for cffi>=1.3.0
Reading https://pypi.python.org/simple/cffi/
Downloading https://files.pythonhosted.org/packages/93/1a/ab8c62b5838722f29f3daffcc8d4bd61844aa9b5f437341cc890ceee483b/cffi-1.12.3.tar.gz#sha256=041c81822e9f84b1d9c401182e174996f0bae9991f33725d059b771744290774
Best match: cffi 1.12.3
Processing cffi-1.12.3.tar.gz
Writing /tmp/easy_install-0s0xymwt/cffi-1.12.3/setup.cfg
Running cffi-1.12.3/setup.py -q bdist_egg --dist-dir /tmp/easy_install-0s0xymwt/cffi-1.12.3/egg-dist-tmp-_1autbm2
c/_cffi_backend.c:15:17: **fatal error**: ffi.h: No such file or directory
#include
^
compilation terminated.
Traceback (most recent call last):
File "/usr/lib/python3.5/distutils/unixccompiler.py", line 118, in _compile
extra_postargs)
File "/usr/lib/python3.5/distutils/ccompiler.py", line 909, in spawn
spawn(cmd, dry_run=self.dry_run)
File "/usr/lib/python3.5/distutils/spawn.py", line 36, in spawn
_spawn_posix(cmd, search_path, dry_run=dry_run)
File "/usr/lib/python3.5/distutils/spawn.py", line 159, in _spawn_posix
% (cmd, exit_status))
distutils.errors.DistutilsExecError: command 'arm-linux-gnueabihf-gcc' failed with exit status 1

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
File "/usr/lib/python3.5/distutils/core.py", line 148, in setup
dist.run_commands()
File "/usr/lib/python3.5/distutils/dist.py", line 955, in run_commands
self.run_command(cmd)
File "/usr/lib/python3.5/distutils/dist.py", line 974, in run_command
cmd_obj.run()
File "/usr/lib/python3/dist-packages/setuptools/command/bdist_egg.py", line 161, in run
cmd = self.call_command('install_lib', warn_dir=0)
File "/usr/lib/python3/dist-packages/setuptools/command/bdist_egg.py", line 147, in call_command
self.run_command(cmdname)
File "/usr/lib/python3.5/distutils/cmd.py", line 313, in run_command
self.distribution.run_command(command)
File "/usr/lib/python3.5/distutils/dist.py", line 974, in run_command
cmd_obj.run()
File "/usr/lib/python3/dist-packages/setuptools/command/install_lib.py", line 24, in run
self.build()
File "/usr/lib/python3.5/distutils/command/install_lib.py", line 109, in build
self.run_command('build_ext')
File "/usr/lib/python3.5/distutils/cmd.py", line 313, in run_command
self.distribution.run_command(command)
File "/usr/lib/python3.5/distutils/dist.py", line 974, in run_command
cmd_obj.run()
File "/usr/lib/python3/dist-packages/setuptools/command/build_ext.py", line 75, in run
_build_ext.run(self)
File "/usr/lib/python3.5/distutils/command/build_ext.py", line 339, in run
self.build_extensions()
File "/usr/lib/python3.5/distutils/command/build_ext.py", line 448, in build_extensions
self._build_extensions_serial()
File "/usr/lib/python3.5/distutils/command/build_ext.py", line 473, in _build_extensions_serial
self.build_extension(ext)
File "/usr/lib/python3/dist-packages/setuptools/command/build_ext.py", line 196, in build_extension
_build_ext.build_extension(self, ext)
File "/usr/lib/python3.5/distutils/command/build_ext.py", line 533, in build_extension
depends=ext.depends)
File "/usr/lib/python3.5/distutils/ccompiler.py", line 574, in compile
self._compile(obj, src, ext, cc_args, extra_postargs, pp_opts)
File "/usr/lib/python3.5/distutils/unixccompiler.py", line 120, in _compile
raise CompileError(msg)
distutils.errors.CompileError: command 'arm-linux-gnueabihf-gcc' failed with exit status 1

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
File "/usr/lib/python3/dist-packages/setuptools/sandbox.py", line 157, in save_modules
yield saved
File "/usr/lib/python3/dist-packages/setuptools/sandbox.py", line 198, in setup_context
yield
File "/usr/lib/python3/dist-packages/setuptools/sandbox.py", line 255, in run_setup
DirectorySandbox(setup_dir).run(runner)
File "/usr/lib/python3/dist-packages/setuptools/sandbox.py", line 285, in run
return func()
File "/usr/lib/python3/dist-packages/setuptools/sandbox.py", line 253, in runner
_execfile(setup_script, ns)
File "/usr/lib/python3/dist-packages/setuptools/sandbox.py", line 47, in _execfile
exec(code, globals, locals)
File "/tmp/easy_install-0s0xymwt/cffi-1.12.3/setup.py", line 248, in

File "/usr/lib/python3.5/distutils/core.py", line 163, in setup
raise SystemExit("error: " + str(msg))
SystemExit: error: command 'arm-linux-gnueabihf-gcc' failed with exit status 1

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
File "/usr/lib/python3/dist-packages/setuptools/command/easy_install.py", line 1131, in run_setup
run_setup(setup_script, args)
File "/usr/lib/python3/dist-packages/setuptools/sandbox.py", line 258, in run_setup
raise
File "/usr/lib/python3.5/contextlib.py", line 77, in __exit__
self.gen.throw(type, value, traceback)
File "/usr/lib/python3/dist-packages/setuptools/sandbox.py", line 198, in setup_context
yield
File "/usr/lib/python3.5/contextlib.py", line 77, in __exit__
self.gen.throw(type, value, traceback)
File "/usr/lib/python3/dist-packages/setuptools/sandbox.py", line 169, in save_modules
saved_exc.resume()
File "/usr/lib/python3/dist-packages/setuptools/sandbox.py", line 144, in resume
six.reraise(type, exc, self._tb)
File "/usr/lib/python3/dist-packages/pkg_resources/_vendor/six.py", line 685, in reraise
raise value.with_traceback(tb)
File "/usr/lib/python3/dist-packages/setuptools/sandbox.py", line 157, in save_modules
yield saved
File "/usr/lib/python3/dist-packages/setuptools/sandbox.py", line 198, in setup_context
yield
File "/usr/lib/python3/dist-packages/setuptools/sandbox.py", line 255, in run_setup
DirectorySandbox(setup_dir).run(runner)
File "/usr/lib/python3/dist-packages/setuptools/sandbox.py", line 285, in run
return func()
File "/usr/lib/python3/dist-packages/setuptools/sandbox.py", line 253, in runner
_execfile(setup_script, ns)
File "/usr/lib/python3/dist-packages/setuptools/sandbox.py", line 47, in _execfile
exec(code, globals, locals)
File "/tmp/easy_install-0s0xymwt/cffi-1.12.3/setup.py", line 248, in

File "/usr/lib/python3.5/distutils/core.py", line 163, in setup
raise SystemExit("error: " + str(msg))
SystemExit: error: command 'arm-linux-gnueabihf-gcc' failed with exit status 1

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
File "", line 1, in
File "/tmp/pip-build-_3eshne2/coincurve/setup.py", line 297, in
**setup_kwargs
File "/usr/lib/python3.5/distutils/core.py", line 108, in setup
_setup_distribution = dist = klass(attrs)
File "/usr/lib/python3/dist-packages/setuptools/dist.py", line 317, in __init__
self.fetch_build_eggs(attrs['setup_requires'])
File "/usr/lib/python3/dist-packages/setuptools/dist.py", line 372, in fetch_build_eggs
replace_conflicting=True,
File "/usr/lib/python3/dist-packages/pkg_resources/__init__.py", line 846, in resolve
dist = best[req.key] = env.best_match(req, ws, installer)
File "/usr/lib/python3/dist-packages/pkg_resources/__init__.py", line 1118, in best_match
return self.obtain(req, installer)
File "/usr/lib/python3/dist-packages/pkg_resources/__init__.py", line 1130, in obtain
return installer(requirement)
File "/usr/lib/python3/dist-packages/setuptools/dist.py", line 440, in fetch_build_egg
return cmd.easy_install(req)
File "/usr/lib/python3/dist-packages/setuptools/command/easy_install.py", line 699, in easy_install
return self.install_item(spec, dist.location, tmpdir, deps)
File "/usr/lib/python3/dist-packages/setuptools/command/easy_install.py", line 725, in install_item
dists = self.install_eggs(spec, download, tmpdir)
File "/usr/lib/python3/dist-packages/setuptools/command/easy_install.py", line 906, in install_eggs
return self.build_and_install(setup_script, setup_base)
File "/usr/lib/python3/dist-packages/setuptools/command/easy_install.py", line 1145, in build_and_install
self.run_setup(setup_script, setup_base, args)
File "/usr/lib/python3/dist-packages/setuptools/command/easy_install.py", line 1133, in run_setup
raise DistutilsError("Setup script exited with %s" % (v.args[0],))
distutils.errors.DistutilsError: Setup script exited with error: command 'arm-linux-gnueabihf-gcc' failed with exit status 1

----------------------------------------
Command "python setup.py egg_info" failed with error code 1 in /tmp/pip-build-_3eshne2/coincurve/
root@0:/home/ZeroNet-py3# uname -a
Linux 0.net.sys 4.5.2-armada375 #1 SMP Tue Oct 25 11:52:56 CEST 2016 armv7l GNU/Linux
```

When i tried to launch zeronet anyway, [there was some errors, i tried to install gevent, but no luck](https://pastebin.com/YH9HUz83).

I have only less than 48 hours on this server as it is expiring.