Stylus gestures features (2/2)

Summary:
Forward-port of https://github.com/CyanogenMod/android_packages_apps_Settings/commit/b3d850521e0042b85422903c70130f350f57b87a
to CM-10.1

Change-Id: I0ab78f1129d2d04b0af21e9b38da027dfe3d1295

Test Plan: depends on D44 no effect on non-stylus devices, test on Note 8

Reviewers: synergy

Differential Revision: http://review.codefirex.com/D45
[2/2] Hardware Keys: port in long press back to kill current app, add to hardware key selections. Reorganize HW key menu a bit.

Summary: part 2 back button long press to kill current app.

Test Plan: Confirm Win!

Reviewers: synergy, randall.rushing, anders3408

Differential Revision: http://review.codefirex.com/D49