Fix tests

[Zlopez]

This fixes tests for fedmsg.

• Fixes docs tox env
• Fixes lint errors

Signed-off-by: Michal Konečný [email protected]

[Zlopez]

I wasn't able to fix python 3.6 and python 2.7 tests.
Python 2.7 tests are failing on import error, which I couldn't figure out how to fix

tox/py27/lib/python2.7/site-packages/py/_path/local.py:704: in pyimport
    __import__(modname)
fedmsg/__init__.py:91: in <module>                                                                                     
    @API_function(doc=fedmsg.core.FedMsgContext.publish.__doc__)   
E   AttributeError: 'module' object has no attribute 'core'        

Python 3.6 is failing on very strange errors (empty body of messages), but because the production machine is RHEL 7 with python 2.7.5 I didn't even tried to fix them, so I don't break something on python 2.7, which I couldn't test