Implement Ros Service to remap one senders messages to / in receiver #10

The UDP bridge receiver is able to receive messages from multiple sending hosts and republishes them under the ROS topic /<originating_hostname>/<original_topic>. It might be usefule to selectively remap one originating hosts messages under / and not under the originating hosts hostname namespace.

One possible solution is to implement this via a ROS-Service which the receiver node can provide.