Neutron Nova Interactions Support

Configure Notification System Options as part of a new class:
neutron::server::notifications.

This class is part of neutron::server because the notifications are sent
by Neutron API service which is configured in neutron-server nodes.

Also add a custom function to map tenant names to tenant IDs.

Change-Id: I57af7cb47a12adabed9b1ee65e1c352b3e5fc2de
Closes-bug: 1306694