liblights: updates & fixes

Fade lights based on ALS value
Add option to disable keyboard or button backlight
Fix some compiler warnings

Signed-off-by: Michael Bestas <mikeioannina@gmail.com>

Change-Id: Ifd6ace89210cab761b38f48225778822236d3f91
Don't build LegacyCamera anymore

Signed-off-by: Michael Bestas <mikeioannina@gmail.com>

Change-Id: Ia68f046f58e8c94189fc2ecce462f09250998ad3