Revert "DocumentsUI: Handle NPE gracefully"

This reverts commit 7734b4fe1fdfe7babcb1a80417bc3a9f719b0557.
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
DocumentsUI: Handle NPE gracefully

Cherry-picked from OmniROM.

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

Change-Id: I8d50d71a9c91486dfc9e5da01538c6b5a626f054
Fix DocumentsUI FC

Change-Id: I2bfd4ea83db53ee83683a4754b49b15cc2abeaca
Implement DocumentsProvider.createDocument and deleteDocument

Fixes AOSPA-431
This is needed to delete and create files/folders in DocumentsUI.
Some open questions are:
1. Are the methods implementented according to their description?
E.g I'm not sure whether deleteDocument should be able to delete folders, too.
2. I first didn't want to modify public API, but deleting files from within DocumentsUI somehow doesn't work - file.canWrite() always returns false
3. So is modfying the API this way OK?

Change-Id: Ie3a9d1888decaa0f08de1a5183ffd23760be15b9