Initial commit of KUKA KR120 support package

Added support for the KUKA KR120 R2500 PRO manipulator
Meshes are based on the Unigraphics files found at http://www.kuka-robotics.com/res/sps/8ba89f50-3ccd-4361-9b9a-60bdd0662ac6_KR120_R2500_pro.prt.zip
Note that the rotation directions of the KUKA manipulators are different than e.g. the ABB manipulator. For joint 1 this is implemented using <axis xyz="0 0 -1"/>.
My personal preference would be to use the naming scheme the mfg uses, but this is actually something we haven't (yet) standardised. Let's wait for some other opinions on this.

The `industrial_robot_client` nodes accept the `controller_joint_names` parameter which makes it possible to use anything (see [wiki.ros.org/industrial_robot_client/generic_implementation](http://wiki.ros.org/industrial_robot_client/generic_implementation)).