django.conf.urls.defaults deprecated in Django 1.6

Use django.conf.urls instead
Version Bumps all around
Django 1.6 and Reversions 1.8 compat
drop django 1.4

we lose 1.4 compat. Rats.
handle a removed field rather than crashing
Merge pull request #23 from Jbonnett/master

Support for django 1.6, reversion 1.8