Reduced some master queries by adding flags to Revision functions.

Reduced some master queries by adding flags to Revision functions.

* The main Revision functions now allow various QoS and locking flags.
* Added tiny DBAO interface add made Revision implement it.
  Since a lot of objects will need (or have) the same functionality.
* Use "self" keyword in Revision class consistently.
* Made Revisison::newFromConds() private.

Change-Id: I3139956999218a2bb44b5c845b8079e33b2328bb