Generic ROS model + urdf checking

This release does not generate an error when the robot does not use all the interfaces.
It is compliant with both normal roscontrol AND the PAL-robotics fork.

Position Control checked on Pyrene

CMakeLists.txt modified to authorize compilation without catkin.
Adaptation of the interface to pure PAL-Robotics forks.
Checked on Pyrene.

Pre-release of version 0.0.1

Adapt to recent changes in ros-control interface from the pal-robotics-fork (0.2.6)