Bump pep8 version to 1.2

Debian Wheezy will ship with this version, and it has many improved checks compared to 0.6, so let's:

- bump version in the docs
- silence some new checks that are wrong due to our indent=2 instead of 4
- fix lots of errors in the code where the indentation was wrong by 1
  or 2 spaces
- fix a few cases of == True, False, None and replace with 'is'
- re-indent some cases where the code is OK, but pep8 complains

Signed-off-by: Iustin Pop <iustin@google.com>
Reviewed-by: René Nussbaumer <rn@google.com>