DocumentsUI: Add a standalone File Manager

This commit adds a standalone mode to the DocumentsUI, to let
it act as a file manager/explorer.
You can browse your storage contents, open files, and delete them,
as well as do everything that the DocumentsUI can do (ie. sort
by name/size/type, list and grid view, recents, search, ...).

This gives us a consistent file browsing UX accross all apps
that uses the new documents API.

Change-Id: If73a3c100f010bdb766c843976d4fd3573ea805c
Es translations
BatteryService: fix FC on boot until battery stat is present

updateLightsLocked() can be called from CM's added SettingsObserver
when battery stat is not present, causing an FC and a loop until
battery stat is present.

I/SystemServer(  502): Battery Service
E/System  (  502): ******************************************
E/System  (  502): ************ Failure starting core service
E/System  (  502): java.lang.NullPointerException
E/System  (  502): 	at com.android.server.BatteryService$Led.updateLightsLocked(BatteryService.java:735)
E/System  (  502): 	at com.android.server.BatteryService.updateLedPulse(BatteryService.java:709)
E/System  (  502): 	at com.android.server.BatteryService.access$1600(BatteryService.java:86)
E/System  (  502): 	at com.android.server.BatteryService$SettingsObserver.update(BatteryService.java:860)
E/System  (  502): 	at com.android.server.BatteryService$SettingsObserver.observe(BatteryService.java:822)
E/System  (  502): 	at com.android.server.BatteryService.<init>(BatteryService.java:187)
E/System  (  502): 	at com.android.server.ServerThread.initAndLoop(SystemServer.java:328)
E/System  (  502): 	at com.android.server.SystemServer.main(SystemServer.java:1309)
E/System  (  502): 	at java.lang.reflect.Method.invokeNative(Native Method)
E/System  (  502): 	at java.lang.reflect.Method.invoke(Method.java:515)
E/System  (  502): 	at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:781)
E/System  (  502): 	at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:597)
E/System  (  502): 	at dalvik.system.NativeStart.main(Native Method)

Change-Id: Ic4438fe50e98f1aa05ae1d0d26240bf9410fd92f