DocumentsUI: Allow open files instead of URIs

Check files' real path and mime type to open them only in standalone mode.
This allows, for example, installing apks.

Change-Id: I4501c694db84b8595cd3928752254a8914539972
Fix: onBoot brightness

When device boots the brightness is always on highest level.

PS1: workaround it
PS2: apply to all devices
PS3: fix blur issue
PS5: sorry, update old file
PS6: remove whitespaces thx Carlo
PS7: revert change in Keyguard, add new fix
PS8: remove tab and whitespace thx Evan

Bug: https://paranoidandroid.atlassian.net/browse/AOSPA-56

Signed-off-by: Matthias Freund <matthias88freund@gmail.com>
Change-Id: I9535e2c22132539e0ad7e9d718b5d0732ba53571