reset stored credentials when call client.logout()
Refactor login template to extend base.

While experimenting with extending DRF, I found that the login page
1) had no title, and 2) duplicated <head> info from base.html.

This change adds a new {% block body %} to the base.html template
which allows override of the entire html <body>. login_base.html
has its duplicated head info stripped, and now extends base.html
to share common html <head> templating.

As part of this change, pretify.css is unnecessarily added to
login_base.html.  If this is deemed a problem, it will be easy to
block that css out, and have login_base.html override the block.

Ideally, I would have liked to create a new api_base.html that extends
base.html, move the api specific logic into that template, and leave
base.html content agnostic, to truely be a unifying base for all DRF
pages.  But this change would break current apps that override
api.html and expect base.html to be the immediate super template. :/

This change is benificial because it:
 - removes duplication of header declarations (mostly css includes)
 - adds a html title to the login page
 - standardizes html header info across all DRF pages

Docs are updated to reflect the new structure.
Updated quick start project set up order
Sending "Bearer" and "Bearer " resulted in a 500.
Updated test docstring related to missing bearer token.
Merge pull request #1705 from opbeat/master

Sending "Bearer" and "Bearer " resulted in a 500.
Issue #1707: Add documentation to api-docs.viewsets notifying users
that they should use the get_queryset() method when overriding a
ModelViewSet method, such as list(). Otherwise, since queryset is
a static property, the value will be cached for every instance of
that ViewSet.
Fix #1712 (issue when django-guardian is installed but not configured/used)
Merge remote-tracking branch 'reference/master'
Django-guardian version cleanup.
Updated the tox file.
Issue #1707 - Add documentation about the caching of `GenericAPIView.queryset`
to the `queryset` property, `get_queryset()`, and do generic-views.md; remove
changes to the viewsets.md documentation from my last commit.
Issue #1707 - Add info about queryset property caching to get_queryset() docs.

Add documentation to the get_queryset() method of generic-views.md regarding
the caching of the queryset property.
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.