The obstacles can now be moved by the robot.

Changed the PID controller of the servos with a compliance controller similar to the one in the real servos.
Changed the control period of the simulated model to 0.001s instead of 0.0078s.
Modified the up and down stairs motions.
Updted the stairs environment to use standard box instead of the stl model.

Added all the STL models and xacro and launch files for the challanges of the CEABOT robot competition, except for sumo.