fix timezone support in wp2zinnia management command

In the WP export, 'post_date' represents the timezone indicated by the server, and 'post_date_gmt' represents GMT (or possibly UTC) for the same time.  On import, the management command is currently using the local timestamp but UTC as the timezone with which to interpret it, making all the times off by the timezone offset.

This solution (for entries and comments) uses the gmt values and 'GMT' as the timezone when saving datetimes.
Removed empty url() references in zinnia wymeditor skins.
Added another css fix missing from last commit
Updating migrations for Django 1.5 compatibility
Adding updates
Merge remote-tracking branch 'upstream/master'
Fixing manager bug
Fixing username reference
Fixing username in feeds
Fixing author username defs
Fixing feed author bug
I should've committed earlier. Down to ~91 failures on python3 and django 1.6
Converted all uses of assertEquals to assertEqual. (That's the only change.)
Small bugfix.
Made the ping-related tests pass. (Down to ~70 failures now). Also removed the six dependency I had added in earlier. (It's built in to django)
Replace pyflakes and pep8 by flake8
Update Makefile and .travis with flake8
Add evolve script to check updates for buildout
Remove write argument for evolve script
Catch all available updates with the evolve script