Fix infinate initial load.

The UserChanges table is a join table comprising of both the Users and
 the Changes tables. When either the Users or the Changes table is
 modified, queries of the UserChanges table may need to refresh.
This notifies that the UserChanges table has been modified when either
 one of its subtables are modified.

It would be good to register a content observer to intercept changes
 and re-broadcast them in the UserChanges table, but this is difficult
 as the database tables are static classes.

Change-Id: I329d08b79e82a00365d8cd1e0f82baaeb704d80b