MediaScanner behavior on boot (1/3)

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: I634ae96b1dcb493b966b4653589cd97523b63da7
(cherry picked from commit 44e913eb5b1890ab5d009530a6b79d21b562742a)

Conflicts:
	core/java/android/provider/Settings.java
[1/2] Base: implement App circle sidebar

add whitelist app to include into circle view
rebased
make standalone patch

PS.15 : rebased
PS.16 : cleanup

Change-Id: I08d2a3a7e0f8df20e801e585d4cac8547a740a3e

@alviteri: crDroid'fy

(cherry picked from commit 2fbc3a50e0b554f2347a63d1f21f76593582e6f3)

Conflicts:
	core/java/android/provider/Settings.java
	packages/SystemUI/res/values/cr_strings.xml