Create DatastoreSnapshotRestore instance via blueprint

Create DatastoreSnapshotRestore instance via blueprint

The DatastoreSnapshotRestore instance was created via a bundle Activator
in order to make it available to both data store instances w/o having to
create a config yang for it and having it advertised as a service and
injected into the data store Modules.

Now that the data store instances are created via blueprint, we no
longer need the Activator and the DatastoreSnapshotRestore instance is now
created via blueprint.

Change-Id: I8299823787fff6b03934e2b0069d77b0d9981d81
Signed-off-by: Tom Pantelis <tpanteli@brocade.com>