Start adding docs for how to test your extensions
Add docs for testing CMS plugins
use django override_settings decorator in cms app test examples
Add mention of CMSTestCase
Use links to django docs

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

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

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