Gathering all expected available robots and parameters in one dict
indexed by names avoid the need to duplicate those informations.

* Added quadcopter Iris from 3DRobotics

* [readme] add hector and iris to the launch command

* [iris] Added reduced version of the STL file

Co-authored-by: PepMS <jmarti@iri.upc.edu>

renamed files

PYTHON_INSTALL_ON_SITE does the PYTHON_BUILD and the INSTALL, but they
require to have the same arguments. Then, we have to put the CMakeLists
in a parent folder of the module, as `python`, or `bindings/python`.

from https://github.com/ros-industrial/universal_robot/tree/kinetic-devel/ur_description