MediaScanner behavior on boot (3/3)

Lets you enable/disable/ask (with a notification) media scanning on boot.
Can speed up boot and reduce initial boot lag from MediaScanner

Change-Id: Ib476117cf1c2b5e8de11a828287c300f30a596b5
Signed-off-by: anerik <anerikgames@gmail.com>

Conflicts:
	res/values/lego_arrays.xml
	res/values/lego_strings.xml
Merge branch 'lego' of https://github.com/LEGO-ROM/android_packages_apps_Settings into lego