epicmtd: Enable camera hardware button as customizable.

Available with the merging of patches:
http://review.cyanogenmod.org/#/c/50631
http://review.cyanogenmod.org/#/c/51189

Change-Id: I71c77bb195c4387030ad79a7b1537133a673202c
Merge "epicmtd: Enable camera hardware button as customizable." into cm-10.2