Add missing abstract method declarations.

git-svn-id: https://svn.erp5.org/repos/neo/trunk@1381 71dcc9de-d417-0410-9af5-da40c76e7ee4

neo/storage/database.py

@@ -75,6 +75,12 @@ class DatabaseManager(object):
     def _begin(self):
         raise NotImplementedError
 
+    def _commit(self):
+        raise NotImplementedError
+
+    def _rollback(self):
+        raise NotImplementedError
+
     def getConfiguration(self, key):
         """
             Return a configuration value, returns None if not found or not set