changed ptu msg from Vector3 (morse) to JointState (real robot)

Fixes #16

In order to control both the real and simulated robot the ptu keyboardcontrol now publishes a sensor_msgs/JointState. In order to control the ptu in MORSE one has to start an extra node that re-publishes the JointState as Vector3 msg.  It can be started as follows:

rosrun strands_utils republish_ptu_jointstate.py