Revert "Switch to flake8 instead of pep8"

We are temporarily reverting this since the new hacking dep breaks setuptools

This reverts commit db2f95ce7a0febb45a59e3fded5effa8a9b10798.
Merge pull request #225 from rackspace-titan/revert-flake8

Revert "Switch to flake8 instead of pep8"