Cleanup collision/auxiliary shapes in urdf

[v4hn]

MoveIt recently changed its policy concerning empty collision geometries. With these changes, the system will warn about visual geometry without associated collision geometries:

ros.moveit_core.robot_model.empty_collision_geometry: Link sensor_mount_link has visual geometry but no collision geometry. Collision geometry will be left empty. Fix your URDF file by explicitly specifying collision geometry. ros.moveit_core.robot_model.empty_collision_geometry: Link double_stereo_link has visual geometry but no collision geometry. Collision geometry will be left empty. Fix your URDF file by explicitly specifying collision geometry.

This pull-request cleans up the PR2 descriptions and removes all useless auxiliary shapes to get rid of these warnings.

Additionally, KDL complains for a long time that the robot's root link must not contain an inertial specification. As the inertial values here are fictitious, I remove them too.

Lastly, the collision geometry of the kinect2 camera did not exist at all (it was practically disabled by a 5mm sphere). I added a bounding box instead, as arm motions with an attached object can indeed reach the spoiler. Here's the before/after pictures for the last change:

@k-okada please review

[v4hn]

CI in this repository is fully broken/outdated. The request is about description changes only though, so CI would not pick up failures either way...

[v4hn]

Thank you for fixing CI @k-okada, please review this now.

[v4hn]

Ping @k-okada

[v4hn]

@k-okada CI succeeded, although it reports it is still waiting for results. Please merge this, it has been lying around for a while now.

Travis had quite a hick-up w.r.t. that issue lately. We have observed the same for a number of requests in the MoveIt repositories.

[v4hn]

Thanks a lot!