Remove deprecated Grizzly features

Now that Havana has started, remove deprecated Grizzly features

* deprecated alias list_notifier_drivers (for notification_driver)
* openstack/common/notifier/rabbit_notifier.py (use rpc_notifier
  instead)

Change-Id: I0dbb997ba774f58766bddf950049ec1e2d5b79de
Merge "Remove deprecated Grizzly features"