Switch to Hacking 0.8 / Pep8 1.4.x

Most other projects use Hacking and flake8 for the
Pep8 checks, which provides signficant advantages:

* Many more checks for typical violations of OpenStack coding guidelines
  (less manual work for reviewers, less style nitpicking)
* more bug fixes in the pep8 checks
* Pyflakes checks - which find usual real coding bugs

Currently most of the checks are disabled via the ignore section
in tox.ini, to be reenabled in later commits.

Change-Id: Iec4d20caf640bd5ca9d796702a6bb1085c60933e
Merge "Switch to Hacking 0.8 / Pep8 1.4.x"