Sync matchmaker_ring.py from oslo-incubator

Cinder does not currently include the matchmaker driver, which is the
preferred configuration with ZeroMQ.

Change-Id: I8514f1780e6492f9d37134d282a5196709347bd8
Partial-Bug: #1185690
Merge "Sync matchmaker_ring.py from oslo-incubator"
(Test commit) Change README to reflect Jio's fork of Cinder

Change-Id: I3f26c0a736e63725aec24ca2fa12c707b8e6460f