Add "Authored" as a default filter to Differential

Summary: Fixes T3786. Not 100% sold on this (I don't want to restore all of the original filters, since users can and should just build the weird ones if they use them), but this is almost certainly the most useful of the defaults which ApplicationSearch removed.

Test Plan: Viewed `/differential/`, executed the query.

Reviewers: btrahan, chad

Reviewed By: chad

CC: aran

Maniphest Tasks: T3786

Differential Revision: https://secure.phabricator.com/D6860