Django-guardian version cleanup.
Updated the tox file.
Fixed the cache issue with Django 1.7 rc*
Fixed the Django 1.3 compat
Better fix for the Django 1.3 compat
Merge pull request #1720 from tomchristie/feature/django_guardian_cleanup

Django & Django guardian updates
Add django-rest-framework-mongoengine link. Closes #1722 Closes #1562 Closes #1545
Add platinum sponsors
Updated Permissions doc link to Django docs

The previous link went to version 1 docs so it was a dead link.
Merge pull request #1724 from kevinlondon/patch-1

Updated Permissions doc link to Django docs
Kickstarter sponsors
Merge branch 'master' of https://github.com/tomchristie/django-rest-framework
Latest sponsor updates
Latest sponsor updates
Fix LaterPay link
Added ProReNata AB
Sponsor updated
Update Nephila sponsorship
Added pathwright
Update sponsorships