https://stackoverflow.com/a/53759308
https://answers.gazebosim.org//question/6416/using_a_urdf_in_gazebo-package-uris-not-described/?answer=6419#post-id-6419
https://answers.ros.org/question/195402/creating-custom-gazebo-world-files-from-sdfsdaes-for-use-with-roslaunch/