KUKA RSI driver / ROS Control hardware interface

This pull-request is meant as a starting point for a discussion about a kuka_rsi_driver. It does not as of now follow the ROS-I driver spec.

The PR implements a fully working system for controlling KUKA robots from ROS using the KUKA.RobotSensorInterface software package. The system is tested on KRC4 controllers running version 8.2.

A video of the running system can be downloaded from [this link](http://folk.ntnu.no/tingelst/2014-06-09_-_IFaCOM_GKN-Demonstrator_-_Robot_Motion_Planning_and_Control.mp4).

The ros-control hardware interface is implemented in the kuka_hw package. KUKA KRL code can be found in the kuka_krl package. A RSI simulator written in python is found in the kuka_sim package.