cut dependency to Kitelab and to jrl-dynamics.

  * Model is found by resource retriever at the location
    package://${modelName}_description.
  * This requires that the robot model install prefix be added to the
    ROS_PACKAGE_PATH environment variable.

  1. Robot description file are now installed. The package does not
     rely anymore on ROS machinery to locate files from package name.
     Instead, the directory where the data relative to the robot are
     installed has been added as an argument of
     hpp::model::urdf::loadRobotModel.
  2. Optional dependency to romeo_description is triggered when corresponding
     test is enabled.

  * This function is now tested in the test display-robot for the
    open-source model of romeo.

 * After a humanoid robot has been loaded with the URDF parser, the
   SRDF file can be parsed to retrieve useful semantic information
   such as collision pairs for motion planning.