ros-control: recipes added.

A set of packages that include controller interfaces, controller managers,
transmissions, hardware_interfaces and the control_toolbox.

The ros_control packages takes as input the joint state data from your robot's
actuator's encoders and an input set point. It uses a generic control loop
feedback mechanism, typically a PID controller, to control the output,
typically effort, sent to your actuators. ros_control gets more complicated
for physical mechanisms that do not have one-to-one mappings of joint
positions, efforts, etc but theses scenarios are accounted for using
transmissions.