Fix primary key configuration in the Ember app.

The Ember Data documentation states that e.g.

    Adapter.map('App.Model', {
      primaryKey: 'uuid'
    });

will work.  That form, however, doesn't set App.Model's primary key via
Adapter to uuid; it'll still be id.

Extending the serializer and defining my own primaryKey function is the
only way I found that actually makes this work.  With this change,
visiting an event_searches.show page now no longer shows duplicate event
types, data collectors, or study locations.