Event District Types

From #114 

Wait a little bit for caches to be cleared out so I can test this...
Ok that's good.

Another idea. Instead of putting the the mapping from a type to string in code, we can build it dynamically when calls to the API are made since event details return both the enumerated district and the district string. So whenever we fetch event details, we update the mapping for the enumerated district to that string. The invariant here is that all events with the same district_enum have the same district_string.