SystemBVT tests

 - Install downloaded app from unreliable source
 - Multiwindow in landscape mode
 - Navigate to new device support settings
 - Camera on lockscreen tests
 - Framework Backup restore tests
 - System Media (Volume = 0 and verify vibrate)
 - Multiuser tests refactor
 - IME tests
 - Settings test fix

Bug: 30948728
Bug: 30974688
Bug: 30975125
Bug: 30975853
Bug: 29393492
Bug: 29360419
Bug: 29395832
Bug: 29396615
Bug: 30945048
Bug: 29415484

Change-Id: Ib716b3d64f3d1530682ef841bc1e46f401ef0114