Add Ceph to Full HA Architecture

The current HA architecture lacks HA for cinder volumes on account of using iSCSI as the backend. We should add Ceph support to the HA architecture. This could largely be a testing and documentation effort since we will have Ceph working in non-HA deployments already per the use-ceph-deploy blueprint. We should consider whether we will deploy Ceph on separate nodes (as we do Swift today) or on compute nodes (as we do iSCSI today). The former is more scalable, the latter requires less hardware.

Note that Ceph is already available in the 3-node HA model. This blueprint would add equivalent roles for the 13-node HA model.