Integration of Xtion into Hera's vision system

[Baggiio]

• [x] Install all necessary packages in order to run Xtion2 bridge.
• [x] Change all vision system topics and frame size to Xtion2.
• [x] Test detector_2d and hera_objects with Xtion2.

If everything works, next step will be to add a Logitech C920 RGB camera on top of Xtion2 and try to synchronize them.

[Baggiio]

Worked. Proceeding to the next step.