Unfrozen future, pep and flakes.

If the reason to keep these at some fixed old versions still exists,
please add a comment.
Fixed a couple of warnings about visual indentation matching logical indentation.

This is not a PEP8 requirement (http://legacy.python.org/dev/peps/pep-0008/#indentation),
but makes the code more readable and above all lets the syntax test stop complaining ;-)

Also normalized on keeping "and" / "or" at the end of a line of a broken conditional for
consistency -- there were just two statements with a binary operator on the following line.
Fixed a couple of block comments not starting with hash and space.
Changed "not page in pages" to "page not in pages" in a test.

Note: the ``test_login_required`` test fails before and after this
change, but that's a different thing (anonymous user accessing a
login-required page gets a 404 rather than a redirect).

On the other hand the syntax test now passes without a note.
Removed a syntax checking exception for mezzanine.utils.timezone.

I believe the module ceased to be deprecated with 769e4f2c2677d56f021a01f77b913d97fff13ae4.
Merge