[2/2] Settings: Configurable overflow menu button

Forward port from SlimBean. It was part of the hardware key custom rebinding.

Change-Id: I2af0c7e7cde1796746331e5a2486bf8ec97f3bb9
settings: Make mobile settings a first-class citizen

 * Nobody likes carriers, but let's not bury these settings behind
   10 layers of indirection. Many users (like me) who travel often
   will need to access these options frequently.
 * The top level switch disables mobile data.

Change-Id: I1bd4d1116a2c73832230d66c94df2c3c0aacf698

Conflicts:
	src/com/android/settings/Settings.java