Start using hacking 0.6

So we can start using new hacking 0.6 checks.

Since hacking 0.6 pins pep8, pyflakes and flake8 they can be removed
from test-requires. For any unfixed checks list them in tox.ini

Fix a H103, 'Header does not match Apache 2.0 License notice' that
leaked in

Change-Id: I652fe3270f1c37afdd386bfae7c4b27b6abcfa06
Merge "Start using hacking 0.6"