Update schema per our new design

We can get rid of EventCurator and EventResource, but I'll wait
until we're completely sure.
BasicDBObject is the implementation, DBObject is an interface.

By extending BasicDBObject, we avoid reinventing the wheel, but when we take args it makes more sense to be general (unless we need some methods like getDate(String key), DBObject only promises "Object get(String key)" iirc.