Bad owner or permissions on machine conf file

Bad owner or permissions on /home/afdaniele/.cpk/ssh/xavier.conf

```
Traceback (most recent call last):
File "/home/afdaniele/.local/lib/python3.6/site-packages/urllib3/connectionpool.py", line 706, in urlopen
chunked=chunked,
File "/home/afdaniele/.local/lib/python3.6/site-packages/urllib3/connectionpool.py", line 445, in _make_request
six.raise_from(e, None)
File "", line 3, in raise_from
File "/home/afdaniele/.local/lib/python3.6/site-packages/urllib3/connectionpool.py", line 440, in _make_request
httplib_response = conn.getresponse()
File "/usr/lib/python3.6/http/client.py", line 1379, in getresponse
self.close()
File "/usr/lib/python3.6/http/client.py", line 969, in close
sock.close() # close it manually... there may be other refs
File "/home/afdaniele/.local/lib/python3.6/site-packages/docker/transport/sshconn.py", line 102, in close
self.proc.stdin.flush()
BrokenPipeError: [Errno 32] Broken pipe

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
File "/home/afdaniele/.local/lib/python3.6/site-packages/requests/adapters.py", line 449, in send
timeout=timeout
File "/home/afdaniele/.local/lib/python3.6/site-packages/urllib3/connectionpool.py", line 756, in urlopen
method, url, error=e, _pool=self, _stacktrace=sys.exc_info()[2]
File "/home/afdaniele/.local/lib/python3.6/site-packages/urllib3/util/retry.py", line 532, in increment
raise six.reraise(type(error), error, _stacktrace)
File "/home/afdaniele/.local/lib/python3.6/site-packages/urllib3/packages/six.py", line 769, in reraise
raise value.with_traceback(tb)
File "/home/afdaniele/.local/lib/python3.6/site-packages/urllib3/connectionpool.py", line 706, in urlopen
chunked=chunked,
File "/home/afdaniele/.local/lib/python3.6/site-packages/urllib3/connectionpool.py", line 445, in _make_request
six.raise_from(e, None)
File "", line 3, in raise_from
File "/home/afdaniele/.local/lib/python3.6/site-packages/urllib3/connectionpool.py", line 440, in _make_request
httplib_response = conn.getresponse()
File "/usr/lib/python3.6/http/client.py", line 1379, in getresponse
self.close()
File "/usr/lib/python3.6/http/client.py", line 969, in close
sock.close() # close it manually... there may be other refs
File "/home/afdaniele/.local/lib/python3.6/site-packages/docker/transport/sshconn.py", line 102, in close
self.proc.stdin.flush()
urllib3.exceptions.ProtocolError: ('Connection aborted.', BrokenPipeError(32, 'Broken pipe'))

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
File "/home/afdaniele/.local/lib/python3.6/site-packages/docker/api/client.py", line 214, in _retrieve_server_version
return self.version(api_version=False)["ApiVersion"]
File "/home/afdaniele/.local/lib/python3.6/site-packages/docker/api/daemon.py", line 181, in version
return self._result(self._get(url), json=True)
File "/home/afdaniele/.local/lib/python3.6/site-packages/docker/utils/decorators.py", line 46, in inner
return f(self, *args, **kwargs)
File "/home/afdaniele/.local/lib/python3.6/site-packages/docker/api/client.py", line 237, in _get
return self.get(url, **self._set_request_timeout(kwargs))
File "/home/afdaniele/.local/lib/python3.6/site-packages/requests/sessions.py", line 555, in get
return self.request('GET', url, **kwargs)
File "/home/afdaniele/.local/lib/python3.6/site-packages/requests/sessions.py", line 542, in request
resp = self.send(prep, **send_kwargs)
File "/home/afdaniele/.local/lib/python3.6/site-packages/requests/sessions.py", line 655, in send
r = adapter.send(request, **kwargs)
File "/home/afdaniele/.local/lib/python3.6/site-packages/requests/adapters.py", line 498, in send
raise ConnectionError(err, request=request)
requests.exceptions.ConnectionError: ('Connection aborted.', BrokenPipeError(32, 'Broken pipe'))

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
File "/home/afdaniele/.local/bin/cpk", line 6, in
run()
File "/home/afdaniele/.local/lib/python3.6/site-packages/cpk/cli/main.py", line 83, in run
res = command.execute(machine, parsed)
File "/home/afdaniele/.local/lib/python3.6/site-packages/cpk/cli/commands/build.py", line 137, in execute
CLIEndpointInfoCommand.execute(machine, parsed)
File "/home/afdaniele/.local/lib/python3.6/site-packages/cpk/cli/commands/endpoint/info.py", line 26, in execute
docker = machine.get_client()
File "/home/afdaniele/.local/lib/python3.6/site-packages/cpk/machine.py", line 106, in get_client
return docker.DockerClient(base_url=self.base_url, use_ssh_client=True)
File "/home/afdaniele/.local/lib/python3.6/site-packages/docker/client.py", line 45, in __init__
self.api = APIClient(*args, **kwargs)
File "/home/afdaniele/.local/lib/python3.6/site-packages/docker/api/client.py", line 197, in __init__
self._version = self._retrieve_server_version()
File "/home/afdaniele/.local/lib/python3.6/site-packages/docker/api/client.py", line 222, in _retrieve_server_version
'Error while fetching server API version: {0}'.format(e)
docker.errors.DockerException: Error while fetching server API version: ('Connection aborted.', BrokenPipeError(32, 'Broken pipe'))
```