New structure for XML parsing - Vehicle sensors - ROSInterface, with an example

These changes will simplify addition of new drivers/sensors and ROS interfaces into UWSim code with as little unneeded changes as possible (currently, only the SimulatedDevices.cpp (out of source files) file must be updated if new driver/interface is added).
It is also easy to convert existing interfaces into this new system, if needed...

Pull request consists of two commits - the first one changes the base code and the second one is an example driver (updated cirs.xml), which outputs a String (configured in driver's XML) on ROS interface.