Support profiling Django 1.3+ CBVs

This allows you to profile methods on CBVs. Since everything is hanging off of
the request object it's still non-trivial to profile other methods (e.g.
get_context_data) but it's at least possible to do this::

    class MyView(TemplateView):
       …

        @devserver_profile(follow=[do_heavy_lifting])
       def get(self, request):
           …