Don't duplicate existing rooms when importing schedule CSV

* Old implementation needs to see exactly the same rooms in exactly
  the same order every time it loads new data, otherwise it will
  create a duplicate entry for the room that differs only in display
  order.
* New implementation ignores the display order when checking to see
  if the room already exists.

vendor/symposion/schedule/forms.py

@@ -96,7 +96,11 @@ class ScheduleSectionForm(forms.Form):
         created_rooms = []
         rooms = sorted(set([x[self.ROOM_KEY] for x in data]))
         for i, room in enumerate(rooms):
-            room, created = Room.objects.get_or_create(
+            try:
+                room = Room.objects.get(schedule=self.schedule, name=room)
+                created = False
+            except Room.DoesNotExist:
+                room = Room.objects.create(
                     schedule=self.schedule, name=room, order=i
                 )
             if created: