Clean up Diffusion dedicated tag table view

Summary: Minor cleanup. Make the "imported" check less strict (we don't need owners or herald to show change status). Export the "imported" flag over Conduit.

Test Plan: Viewed tag table. Viewed partially imported repositories.

Reviewers: btrahan

Reviewed By: btrahan

CC: aran

Differential Revision: https://secure.phabricator.com/D7455