Remove backward compatibility for old settings
Remove backward compatibility for old settings

The old settings have been deprecated for quite some time.

This fixes richleland/django-cumulus#117

bennylope/django-cumulus,CoachLogix/django-cumulus,bennylope/django-cumulus,ImaginaryLandscape/django-cumulus,elsmorian/django-cumulus,ferrix/django-cumulus,rizumu/django-cumulus,mandx/django-cumulus,elsmorian/django-cumulus,django-cumulus/django-cumulus