Summary: Ref T10537. This adds an update daemon for pulling item data (e.g., figuring out who the author of a GitHub comment is) and routing items (e.g., sending them to a queue or applying them directly to a task). Also adds `bin/nuance update --item X` for doing this manually for debugging. And adds item types, for specializing item behavior. Previously, sources completely dictated item behavior, but I think we want something a little more flexible. Test Plan: - This still does nothing. - Ran `bin/nuance update --item 15`. - Saw an item route to a default queue. Reviewers: chad Reviewed By: chad Maniphest Tasks: T10537 Differential Revision: https://secure.phabricator.com/D15441