improve asynchonous publishing performance (fix #373)
Transport information in SlaveAPI::getBusInfo() for `roscpp` and `rospy` nodes

- The information looks like 'TCPROS connection on port X to [Y:Z on socket S]'
- The information can be retrived by using getBusInfo() XMLRPC call to a roscpp/rospy nodes (added as an extra field to the end)
- UDP is not supported yet for rospy