add retine loader
adds retina arrows for collapsable states
Add tests for permissions cache
Start adding docs for how to test your extensions
Add docs for testing CMS plugins
set latest retina wrapper and add high dpi loader
remove tabs
Merge branch 'develop' of github.com:divio/django-cms into develop

Conflicts:
	cms/static/cms/css/plugins/cms.placeholders.css
	cms/static/cms/css/plugins/cms.toolbar.css
Merge pull request #1808 from FinalAngel/develop

Frontend Fixes
Merge branch 'develop' of github.com:divio/django-cms into develop
use django override_settings decorator in cms app test examples
undo/redo working with adding and removing plugins
Add mention of CMSTestCase
Use links to django docs

as suggested by @piquadrat
test docs again
Add link to reverse() function

from testing docs
fixed tests
Merge pull request #1807 from foobacca/testing_docs

Testing docs
Removed unused imports
Merge branch 'support/2.4.x' into develop