[Android] Implementation of the keyboard basic controls

[Alexandre Perraud]

First bunch of patches for keyboard and Android TV navigation.

[PATCH 1/5] Video: implementation of the keyboard basic controls
[PATCH 2/5] Video: add mute control from keyboard
[PATCH 3/5] Video: add volume control from keyboard
[PATCH 4/5] UI: Cosmetic fixes when some elements are focused
[PATCH 5/5] Video player: modify focus behavior for keyboard