Themes: add ability to theme quick settings battery tiles

This is to make the battery tiles more uniform to the rest
of quick settings and also allow the background to be themed

http://i.imgur.com/AA5bkMK.png

Change-Id: Iec03572a0fa3619d2652f30b6c260a278ed0c86b
Themes: Use default_wallpaper for HOLO lockscreen wp

Change-Id: I9c7fd29c99d13e811993eb9b3b045010431ccad0
DocumentsUI: Handle NPE gracefully

Cherry-picked from OmniROM.

http://jira.omnirom.org/browse/OMNI-956

Change-Id: I8d50d71a9c91486dfc9e5da01538c6b5a626f054
DocumentsUI: Remove catch-all statements

This removes several "catch (Exception)" statements which violates the Android code
style guidelines and hides problems.

I left some catch-all statements in, as they seem to be intended like this (grep for
"catch (Exception").

I suggest we do not merge this before we are sure that we fixed any problems. One problem
is a crash when deleting items (I'm currently working to fix that).

PS 2: Add exception to log.
Change-Id: I483c320c7ee256acd993dd2a509c031fa5e3f09e