Fixed #6735 -- Added class-based views.

This patch is the result of the work of many people, over many years.
To try and thank individuals would inevitably lead to many people
being left out or forgotten -- so rather than try to give a list that
will inevitably be incomplete, I'd like to thank *everybody* who
contributed in any way, big or small, with coding, testing, feedback
and/or documentation over the multi-year process of getting this into
trunk.

git-svn-id: http://code.djangoproject.com/svn/django/trunk@14254 bcc190cf-cafb-0310-a4f2-bffc1f526a37