Adds ability to answer call with hardware HOME button (preparation to winter time)

Change-Id: Ic11449acf87c6b4d932142b74158af7441658b3d

Patch set 1 : Upload the change
Patch set 2 : Only change the real Author
Patch set 3 : Bugfix:
              Add register for the ContentObserver (Settings.Secure.RING_HOME_BUTTON_BEHAVIOR) in PhoneWindowManager,
              and correcting the logging functions and deleting some unneeded comments