Add support for iCub facial expressions simulation in Gazebo

[traversaro]

Probably this can be done with the gazebo_yarp_videotexture plugin, as done for the R1 robot ( https://github.com/robotology/cer-sim/issues/17 and https://github.com/robotology/cer-sim/pull/18).

Other related issues:

• https://github.com/robotology/gazebo-yarp-plugins/issues/132#issuecomment-219767806
• https://github.com/robotology/QA/issues/403