Lockscreen : Vol long press skip tracks (1/2)

Straight port from cm7

Credit : Kmobs,Sven,Cvps..and all who've refined it

Patchset 2 : Minor fixes
Patchset 3 : Fix misplaced closing bracket
Patchset 4 : Rework the conditional logic
Patchset 5 : Rebase
Patchset 6 : Fix vol change for wake screen
Patchset 7 : Cleanup

Change-Id: I74584932772ddabbd203acb4d6a65270fd6b20c2