zip_safe mode is broken

Copied from #189

without the zip_safe set to False when setuptools installs the library
either using easy_install, setup_requires or install_requires these warnings
get produced. The issue lies in the use of a CI service like Appveyor, the
warnings are output using stderr and this triggers the build to fail.

```
zip_safe flag not set; analyzing archive contents...
comtypes.__init__: module references __file__
comtypes.client._code_cache: module references __path__
comtypes.client._generate: module references __file__
comtypes.client._generate: module references __path__
comtypes.server.register: module references __file__
comtypes.test.TestComServer: module references __file__
comtypes.test.TestDispServer: module references __file__
comtypes.test.__init__: module references __path__
comtypes.test.test_dispinterface: module references __file__
comtypes.test.test_findgendir: module references __path__
comtypes.test.test_safearray: module references __file__
comtypes.test.test_server: module references __file__
comtypes.test.test_urlhistory: module references __file__
comtypes.test.test_win32com_interop: module references __file__
comtypes.tools.codegenerator: module references __path__
```