Diffusion - move build refs to occur over Conduit
Summary: Ref T2784.
Test Plan: loaded up a git commit with refs and they showed up! loaded up a git commit without revs and nothing showed up.
Reviewers: epriestley
Reviewed By: epriestley
CC: aran, Korvin
Maniphest Tasks: T2784
Differential Revision: https://secure.phabricator.com/D5957