Fix serialization

Serialization was broken while working on the persistence feature.

This patches fixes serialization and deserialization code, including
some out of sync internal lazy loaded attribute that got out of sync
with the OVO when a volumes was created.

cinderlib/persistence/base.py

@@ -29,6 +29,9 @@ class PersistenceDriverBase(object):
     updated, and removed, as well as provide a mechanism for users to retrieve
     volumes, snapshots, and connections.
     """
+    def __init__(self, **kwargs):
+        pass
+
     @property
     def db(self):
         raise NotImplemented()