Improved coding style viewset.py, moved get_url_pattern to class.
Reworked viewset declarations to use AmCATViewSetMixin
can_create / can_update remove from AmCATModel, changing project.py to reflect these changes.
Cleaned Annotator JS; now uses new API more.
Models can't be defined on mixins, without reversing inheriting order. Moved models back into ViewSets.
Automatic lookup now occurs for getattr(viewset, viewset.model_key), which resolves to viewset.model.objects.get(pk=self.kwargs[model_key]). Changed all viewsets to support this change (removed dead code).