Add registry and role service list entries for Octavia

Add registry and role service list entries for Octavia

This patch adds the Octavia services to the registry and controller role
(disabled by default). Also included is an example environment file for
enabling the services and required configuration. The API service
profile is also amended configure the load balancer service provider in
neutron to point to the octavia load balancer driver.

Change-Id: I7f3bba950f5b1574ba842a39e93a8ac2b1ccf7bb
Partially-implements: blueprint octavia-service-integration