Update models with realistic viscous and coulomb friction parameters about icub-models

[diegoferigo]

I want to bump this issue since it is affecting all our simulations. Is there available any (even unofficial) list of recently identified friction parameters? I don't think that these parameters should be extremely accurate, having at least the right order of magnitude would help a lot. I fear that setting kv=1 is quite a high number.

cc @robotology/iit-dynamic-interaction-control

[traversaro]

Good point, I think that the one that most recently worked on this is @nunoguedelha . To clarify the historic setting, a quite high damping was actually choose to reduce the numerical noise when simulating the model in Gazebo with the ODE physics engine, but as we discussed in #33 it is quite important that for the future we try to keep strictly separate the "nominal" model parameters, and any simulator-specific hack.

cc @pattacini @Nicogene