Search for free port for broker

Setting the local port to zero causes the broker to search for a free port.
In nao_robot/nao_apps/nao_tactile.py this technique is used to make the broker
search for a free port. However this does not appear to be a documented
by aldebaran.
Merge pull request #7 from jondy276/search-for-free-port-cpp-naonode

Search for free port for broker