Added a test for implicit primary keys which unearthed a bug where the primary key type was being left as default and not being set from the model.  This fixes that.
Few more resource tests...safety checkin before I do a refactor of the TGRESTServer.
Refactored to move the datastore out of the REST server into subclasses of an abstract class.  This is way cleaner and it allows for both a nice separation of concerns as well as future datastore types that anyone can add.