framework/base: Add EdgeGesture service.

Based on code of PieService.

Change-Id: I053737e36340a5ec6814b21eb87575f9689c7e88

Conflicts:

	core/res/res/values/config.xml
	core/res/res/values/symbols.xml
PhoneWindowManager: add ability to use Pie service for system gestures.

Change-Id: Id4e2c0d82f771cd1c20e9196fb6db347494cca69
Keyguard: fix statusbar lags when default widget shown.

When statusbar became expanded KeyguardStatusView receives
onKeyguardVisibilityChanged callback and refreshes ClockView.
Because it receives more than one call and every time it reads
new values from resources it cause lags in opening statusbar panel.

Replace this code with BroadcastReceiver and ContentObserver to
refresh it only in case something was changed.

Change-Id: If0dbc1db059536806852661931cb2e6436f2acf4