NX: Swipeable interface separating action dispatch from implementation

Make NxGestureHandler not care about what happens when a motion event
is detected. This will be useful when attaching a editor which will
do completely differnt things with detected motions

PS1: Add public call to notify of screen-off. Reset DT flags
     May change to BroadcastReceiver to get notified of
     screen-off events. Maybe.

PS2: Indentation and white space cleanup

PS3: Introduce split bar tap detection and fix isEnabled() logic
     single tap / double tap / long tap left and right are now
     separate actions. When only one action is set, the entire
     bar exectutes the action. We are using the single action
     uri as the right side uri so the behavior for the user is the
     same

Change-Id: Ie32204cf871d969ed40a3f0cb7feae20e35c9bef
Fix NPE in internal SystemUI UiController handling

Change-Id: I8a9027d74b0bcffe34468cd4eec99064dabf042b