This adds another environment to the uol and tum class of environments including a human for HRI research

It uses a specialised class of the Morse human implementation that features a more detailed collision model allowing to see the individual legs in the laser scan (the collision model of the original Human model in MORSE simply uses a bounding box, rendering the human as a box in the laser scan). So far, only the legs are modelled for collision, later for the kinect to work we could extend this so that also the upper body returns readings properly. Also, I changed the colours of the human model :-)
The new human model is called HumanStrands. This pull request doesn't change anything in the behaviour of the other environments without humans, so it should be 100% safe.