Users of the oslo.messaging RPC communications service must use
the rabbit ("rabbit://...") or AMQP 1.0 ("amqp://...") drivers.
Change-Id: If3474142f1fe99d41d7b4466061ed0e23ca38549
Closes-Bug: 1789259
ZeroMQ driver options are current stored into the DEFAULT group.
This change makes the zmq configuration clearer by putting its
options into oslo_messaging_zmq group.
Change-Id: Ia00fda005b1664750d2646f8c82ebdf295b156fb
Closes-bug: #1417040
Co-Authored-By: Oleksii Zamiatin <ozamiatin@mirantis.com>