Add TransactionFilter to make sure transactions are being
closed/commited
JDO layer cleanup

- Rename TransactionFilter to PersistenceManagerTransactionFilter
- Remove Transaction management from DatastoreFacade - now the
  PersistentTransactionFilter takes care of rollback active transactions
- Make GenericDAO.get throw ObjectNotFoundException instead of returning
  null
- Add method to JDOGenericDAO to get an active Transaction
- Make JDOGenericDAO not abstract anymore
Handle error when watchdog isn't installed
Add jdo enhance task
Change handlers to use DB