[freeipa PR#1122][opened] travis: make tests fail if pep8 does not pass

[stlaz]

   URL: https://github.com/freeipa/freeipa/pull/1122
Author: stlaz
 Title: #1122:  travis: make tests fail if pep8 does not pass 
Action: opened

PR body:
"""
Currently, pep8 does not seem to fail even though there may be errors, let's see if
this helps it.
"""

To pull the PR as Git branch:
git remote add ghfreeipa https://github.com/freeipa/freeipa
git fetch ghfreeipa pull/1122/head:pr1122
git checkout pr1122