Make base class NOP rather then error

Change-Id: Ib054a293a29d060966f4ca9c9f7672b640834d42
Rename functions to clarify usage.

Change-Id: I5d7c0a9dba7cf22176e889fa563c0ffa1c1ea91e
Merge datastores.

Change-Id: Iddbd39bee21cef58aaed2e5fbe5b93a346a19985
Change method order.

Change-Id: Ia69853549feaba8486a3bf520e7d90457072b3b1
Add more datastore methods.

Change-Id: I4a528832f903c4c194c0d022f7d3220eb39f302d
Only process each datastore once.

Even if datastore name mentioned by multiple machine_categories, we only
need to process each one ONCE.

Change-Id: I299548e6dba3eec7753b43962a387fb7ee6ec87a
Move ldap datastore settings.

Change-Id: Ia8021a17c22c536a3cc1968286ac482de4ebc83b