Fixed #11410 -- Moved the "Groups" field to the "Permissions" module in the...

Fixed #11410 -- Moved the "Groups" field to the "Permissions" module in the `auth.User` admin form and modified the help texts for the `user_permissions` and `groups` model fields to reflect that change. Also did a little PEP8 cleanup and improved some docstrings while I was in the area. Thanks to benspaulding and Aymeric Augustin for the suggestions.

git-svn-id: http://code.djangoproject.com/svn/django/trunk@17325 bcc190cf-cafb-0310-a4f2-bffc1f526a37