Redefined several classes as subclasses of the implementations in backend.py. Removed PersistenceService.
Redefined several classes as subclasses of the implementations in backend.py.
Removed PersistenceService.

--HG--
extra : convert_revision : svn%3Ae60b0d31-0b1b-0410-851a-a02d0c527677/trunk%4047

ralphm/idavoll