Sync rpc from oslo-incubator.

This includes rpc api namespace support, some minor configuration
related fixes, and the redis based matchmaker for use with impl_zmq.

Change-Id: I9fc826a498461417afe8b2a923edac8d68c2c18f
Merge "Sync rpc from oslo-incubator."
Merge remote-tracking branch 'm_src_repo/citrix-fixes' into build-temp