Add a script for testing pep8/pyflakes

The script will be used by Makefile rules and by a pre-commit-hook that will
call it soon on git-stoq.

Solve some pyflakes/pep8 problems too since jenkins will test them all now.

Change-Id: Ide3b00ab87fcd12054cd1a1b509a41f8d1950d12
Update pep8 to version 1.4.4

Version 1.4.4 has a lot of fixes, and one that is important for us that is the
support for sphinxs documentation (i.e. '#: ').

Change-Id: I45a39f26ddf578037485717aa8da1b400130fde6