PowerManager: Don't wake up device when charger is plugged/unplugged (2/2)

This will add the option to disable waking up the device when a charger
is plugged or unplugged.

added as well config option to disable volume rocker wake for devices
which do not support it well

Change-Id: Idf37087b4cdee94c8557d67ab3d491d65bc60c36

Conflicts:
	res/values/slim_strings.xml
	src/com/android/settings/DisplaySettings.java