Update robot mass on latest devel/master

[liesrock]

@aled96 can you work on the above based on the mass sent by Lorenzo?

Please create a branch and tomorrow we can do a PR.

[liesrock]

@aled96 is working on this, thanks a lot!

[aled96]

For now I created a branch head_mass in which I update the mass/inertia values for the main element of the head, while the supporters for the 2 sensors (D435 and Velodyne) are still missing.