Although we eventually want to handle indexing via a third-party
service, add a rough facility for doing it via an admin interface.
This is a temporary solution, though not necessarily a bad one.
A generic CUD callback mechanism has been added to the EntityDAO
and handlers wired up in the Global object to update Solr whenever
they are called. This seems to work more or less, although there is
some ugliness caused by our decision to index descriptions instead of
the master object, which means there's a slight mismatch between what's
going on in the DB and the index.