s4-common: move hardware button config to device files

Allows camera button remapping to be possible for jewel

Requires:
http://review.cyanogenmod.org/51679
http://review.cyanogenmod.org/52230
http://review.cyanogenmod.org/52228
http://review.cyanogenmod.org/52225

Change-Id: Iaf8ca430d43131435080a7bf26e98d0e35ec7ac7
Merge "s4-common: move hardware button config to device files" into cm-10.2