Monitor broker instances with monasca

It should be possible for a user to have the broker VMs send monitoring data to a Monasca endpoint. Given that Cue is an Openstack service, deeper integration with Openstack services like Monasca would make a lot of sense. We should provide an option for users to specify Monasca credentials to have Cue set up a monasca agent and have monitoring data for the broker be sent to Monasca.