Notification Power Widget: Real rotation lock using ICS API:s

Old implementation of auto rotate button just toggles auto rotation.
New implementation use the new rotation freeze/thaw API:s. Accelerometer
is toggled like before, but current rotation is kept ("frozen"). This
means that AutoRotateButton now works like the rotation lock button
on iOS devices and the native rotation lock button in ICS on tablets.

Change-Id: I8e32bafe46f316194fdf77c375e1adbb7edcf50f