layout: fix tutorial layout issues

On small screens, the button was not really
visible.

Signed-off-by: Blechd0se <alex.christ@hotmail.de>
misc: add vibrator control for other devices

The nexus 4 uses a slightly different path, add it.
Also changing the behaviour of the empty preference
to only show it on devices with onscreen navbars.

Signed-off-by: Blechd0se <alex.christ@hotmail.de>
helpers: allow to toggle empty prefernces

Allow to control whether we want to add an empty
view or not.

Signed-off-by: Blechd0se <alex.christ@hotmail.de>