refactor Ceph mon.pp

 * drop keyring file declarations, check for ceph-create-keys instead of
   running ceph-deploy gatherkeys to check for Ceph cluster quorum
 * move Ceph client ACLs definition to cinder.pp and glance.pp
 * extract c_pools subclass into a proper ceph::osd_pools class
 * parametrize Cinder and Glance pool names explicitly and separately
   instead of accessing them by indices in a list
 * drop the checks for $::glance_api_conf and $::cinder_conf