Ensure RabbitMQ is restarted after config changes

Restart RabbitMQ after a change to the:

- SSL Certs
- Erlang Cookie
- RabbitMQ Config

Change-Id: Ie2f05ca700e5e23d25abcd4fe3ccb4e74529d5c4
Create a cluster dict in the rabbitmq pillar

Use this new dict to populate entries in /etc/hosts for the rabbit
cluster, and also use it for the node list in
/etc/rabbitmq/rabbitmq.config (falling back to the old nodes list in
pillar).

Change-Id: I9c08c3af1821fb8680d6537442e96f8abb60445f