DocumentsUI: catch berserk apps on building recents

We should not crash Documents app because of that

Change-Id: Ie89a10c5005aef7f3e75a4f5a17f018e0fbc0814
DocumentsUI: fix recursive delete

Create one DirectoryLoader in UI thread to use for delete

Change-Id: I83a5811f152090f7812ad58ff4ee3bc13748d158