Decouple SD card from ADVANCED storage toggle.

A variety of related fixes:
- don't force size enable when browsing from device mounted notifications.
- don't show settings menu item as action (put in overflow).
- add sd card icon (not quite yet used, need to suss that out).

Bug:26880985,26883578,26771127
Change-Id: I36f153c42217f8092f157ded2a756c02525593ab