MediaProvider: support streaming bookmark

Add bookmarks table and bookmark URI.

CRs-Fixed: 637282
Change-Id: I4414a1619066efe58457350a82394d56d26d41bb
MediaProvider: Avoid issue of android.process.media stop

"OK" and "Cancel" button's click event response at the same time
lead to FATAL EXCEPTION. Make the click events do not happen at
the same time.

CRs-Fixed: 513752
Change-Id: I92fc1dc15be42d0bd9fe54f41fdbb26b3ca4b85c
MediaProvider: MediaScanner behavior on boot (2/3)

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

- added xxhdpi icon
- no need for multiuser due that this should be a one time set
  general option set by the owner of the device

Change-Id: Iad0b72f8b653b3d567b27de3ccf5c6cfb07e40ed