UMS [1/6]: LegacyUSB Squashed commit with updates for 4.2

LegacyUSB: add overlay for UMS lun and use existence of lun to enable legacy USB
LegacyUSB: Add support for legacy USB implementations
Option to hide Adb notification icon (framework) - authorship belongs to Rick C

2: https://gerrit.omnirom.org/#/c/5042/
3: https://gerrit.omnirom.org/#/c/5043/
4: https://gerrit.omnirom.org/#/c/5044/
5: https://gerrit.omnirom.org/#/c/5045/
6: https://gerrit.omnirom.org/#/c/5046/

Signed-off-by: Humberto Borba <humberos@gmail.com>
Change-Id: Id14f70f7e21b689c08cadef69f69da711c7dc566
Merge "UMS [1/6]: LegacyUSB Squashed commit with updates for 4.2" into kitkat