[zmq] Reduce number of connections

In this change 'use_router_proxy' option was added
to switch between direct connections and proxy.

Proxy was reimplemented and splitted onto two
types of proxies:

    * PUBLISHER proxy for fanout pattern
    * ROUTER proxy for direct messaging

Each type of proxy is configured over command line
argument --type.

Deployment guide was updated accordingly to the change.

Change-Id: If36e9c26e2a8ebe622cfa7e9f2a07b1a69aabe34
Closes-Bug: #1555007

oslo_messaging/_drivers/impl_zmq.py

@@ -83,6 +83,9 @@ zmq_opts = [
                 help='Use PUB/SUB pattern for fanout methods. '
                      'PUB/SUB always uses proxy.'),
 
+    cfg.BoolOpt('use_router_proxy', default=False,
+                help='Use ROUTER remote proxy for direct methods.'),
+
     cfg.PortOpt('rpc_zmq_min_port',
                 default=49153,
                 help='Minimal port number for random ports range.'),