DocumentsUI: fix recursive delete

Create one DirectoryLoader in UI thread to use for delete

Change-Id: I83a5811f152090f7812ad58ff4ee3bc13748d158
Externalize symbol picker options to resources

Having the symbol picker options in resources allows a change to be made for
a specific device, and even for a specific locale (change in overlay).

Ported from cm10.2: http://review.cyanogenmod.org/32581

Signed-off-by: Michael Bestas <mikeioannina@gmail.com>

Change-Id: I72ff6fab6b9c14f9761904fdcc6918784d790d4d
Merge pull request #9 from omnirom/android-4.4

Merge into kk4.4