Fix migrations for trashbin feature

dav_events/views/events.py

@@ -293,16 +293,14 @@ class EventRegistrationsView(EventPermissionMixin, generic.DetailView):
             'purge_at': registration.purge_at,
         }
         participant = models.Participant.objects.create(**data)
-        registration.accepted()
+        registration.status.set_accepted()
         messages.success(request, _(u'Teilnehmer hinzugefügt: {}'.format(participant.get_full_name())))
 
     def _reject_registration(self, registration):
-        registration.rejected()
+        registration.status.set_rejected()
 
     def _reset_registration(self, registration):
-        registration.status.accepted = None
-        registration.status.answered = False
-        registration.status.save()
+        registration.status.reset()
 
     def _swap_participants_position(self, participant1, participant2):
         event = participant1.event