Changing location of LOOKUP_SEP for Django 1.5.

That lookup has changed locations.
Adding 'django.contrib.auth' to installed apps.

Makes the default User implementation work, and fixes those
could not import errors.
Fixes deprecation warnings when runing tests.
Updating to match Tastypie's new method signatures.
Merge pull request #7 from willvanwazer/master

Django 1.5 compatibility