Added node that fakes missing topics in MORSE, e.g. /motor_state

Added a simple node (scitos_node) that publishes topics and provides services according to the real robot.

This node runs in parallel to morse and thereby complements it by providing missing topics such as /motor_state.
As this node should be launched whenever the scitos robot is used in MORSE, I added a launch file called scitos.launch, which now bundles the scitos robot state publisher and the scitos_node. I included this new launch file in all existing simulations (bham,tum,uol). That is, future changes wrt to the robot should be realized within scitos.launch instead of the individual environment launch files.

Closes #44