Fix the What's New? phabricatorbot handler.

Summary: What's new has been broken for awhile, I've updated it to use the feed.query text view.

Test Plan: Start up a bot and say "What's new?"

Reviewers: epriestley, Blessed Reviewers

Reviewed By: epriestley

CC: fas, epriestley, aran, Kage, demo

Differential Revision: https://secure.phabricator.com/D8118