Summary: Ref T2625. Lifts almost all of the search logic out of Paste controllers and into Search. This uses controller delegation for generalization. We use this in a few places, but don't use it very much yet. I think it's pretty reasonable as-is, but I might be able to make even more stuff free. There are some slightly rough edges around routes, still, but I want to hit Phame and Differential (which both have multiple application search engines) before trying to generalize that. Test Plan: Executed, browsed and managed Paste searches. Reviewers: btrahan Reviewed By: btrahan CC: aran Maniphest Tasks: T2625 Differential Revision: https://secure.phabricator.com/D6073