Fix "Attach <x>" dialog showing too much stuff

Summary: After the recent search changes, the filter here changed from `type` to `types`. Currently, if you click "Attach Differential Revisions", it shows objects of too many types.

Test Plan: Clickced "Attach Differential Revisions" or whatever it's called, just saw revisions.

Reviewers: btrahan, chad

Reviewed By: chad

CC: aran

Differential Revision: https://secure.phabricator.com/D8164