Bring in velocity/Cartesian controllers

Thought about bringing in this PR so that we can discuss it in order to improve it.
It's not perfect yet and it still has some known issues:
- still contains yaml's and launch-files (see #134)
- still prone to singularities (cob_twist_controller, cob_lookat_controller)
- handling joints and velocity limits needs to be improved

But it is already used by:
- cob4-1 (simulation) for teleop and odometry_monitor
- raw3-3 (hardware) handle tracking