Stop including full service catalog in each RPC msg

The service catalog is included in the context to get the cinder API
endpoints.  Instead of passing entire service catalog just for cinder
endpoint, just include cinder endpoint in context.service_catalog

Change-Id: Ic39173f0a2f330dbd78daa786b269f29ac4abf33
Merge "Stop including full service catalog in each RPC msg"
Merge remote-tracking branch 'citrix/master' into build-temp