Fix IPC direct topic routing.

Direct messages were being stripped of the host
value when performing IPC forwarding. This caused
direct topics to be round-robined to all
services running on the system consuming from
the same base topic name.

i.e. if 'scheduler.host1' and 'scheduler.host2'
were running on the SAME machine, messages to
'scheduler.host1' may have been routed to
'scheduler.host2'.

Now, mulitple processing specifying different
rpc_zmq_host parameters will consume on
separate direct topics and will not
round-robin to other processes.

Adds a zmq-specific test to ensure that messages to
directed topics are not consumed by other
consumers of direct topics sharing a bare
topic on the same host.

Fixes bug 1123715

Change-Id: I939c24397e58492fc16561666aed3ca891325e9c
Merge "Fix IPC direct topic routing."