LUN-943 -- Make sure the groups change list doesn't contain duplicate entries by making a distinct on the returned queryset
Use the reciever decorator for making the singal handlers more readable
Break the unit tests in multiple classes for better readability
Do proper cleanup when deleting a group that a role is built on top of
A more readable/understandable comment
Improve the speed at which auto-generated groups get updated by only running the signal handler for post_* actions
Remove code that was handling an exception that would have never been raised
Fix typos and bad grammar in the documentation
Add a nice diagram on how site wide roles work
Merge pull request #13 from pbs/LUN-943

LUN-943 -- Make sure the groups change list doesn't contain duplicate entries by making a distinct on the returned queryset
Bump version as instructed by bamboo
removed duplication and prefetch related (not needed because permissions are not read but are written afterwards)
Merge branch 'master' into non-site-wide-UI

Conflicts:
	cmsroles/models.py
LUN-826 Create a more complex page hierarchy for the purpose of testing and rename a couple of tests
LUN-826 Written unit tests for the page selection functionality and made a couple of improvements to the views:

* class PageFrom is no longer duplicated in two views
* when the user formset is submited, if a user didn't change he's role don't ungrant and regrant the same role