bug 7599 performance improvement for ucast macs

bug 7599 performance improvement for ucast macs

Using the getModifiedChildren api on the modification to identify the
modified children data under node.

updated data and deleted data is stored in operational state for access
by all the commands.

Added the following accessor methods in operational state.
List<? extends Identifiable> getUpdatedData(InstanceIdentifier<Node> key,
Class<? extends Identifiable> cls)
List<? extends Identifiable> getDeletedData(InstanceIdentifier<Node> key,
Class<? extends Identifiable> cls)

Change-Id: I76584d7c90323313da35e28a600019c05081f9d0
Signed-off-by: K.V Suneelu Verma <k.v.suneelu.verma@ericsson.com>