Don't give a default port to the rt client

This prevents all the rt clients in the same rtclient-cluster from
trying for the same port at the same time.

Changed options:
* portBase is the number to which we add a random number to get a
random port.
* port is a hard port number, be careful when using it in clusters.

Change-Id: I8c212cee229a20622e4901f57c844546a61a8c06