Revert "Implement DocumentsProvider.createDocument and deleteDocument"

The original commit breaks the public API and causes crashes when
deleting certain items in DocumentsUI

This reverts commit f6bfaee6ad7ccd4491609d5df606558a4ae30f72.

Change-Id: I5a433148548e7a1a997ee50e5938f7a4cb4c5ade