Added rabbitmqadmin and enabled management plugin

Useful for debugging issues with rabbit, and inspecting the queues.

* Enabled the management plugin
* Created a provider_admin user with the admin tag.  This user has
  access to the management interface.  Opted not to give the default
  'openstack' user these permissons (altho I don't think it would hurt).
* Wrote integration tests to confirm this setup.