improve simulation

[marc-hanheide]

• [x] put camera on the arm (e.g. look at http://www.youbot-store.com/wiki/index.php/Microsoft_LifeCam, http://gazebosim.org/tutorials?tut=ros_gzplugins#Camera, http://www.generationrobots.com/en/content/75-gazebo-and-ros)

[Jailander]

@webbam46 has a dded a cube with the circular pattern but he will modify it so it looks like a circle on a stick with a cubic base. Dimensions are for him to choose somewhere between 5 - 8 cm diameter for the circle

[marc-hanheide]

We need to turn the target into a model that we can 3D print as well