R1:80378eb5f6a8

Show policy information in Differential header

Summary: Ref T603. Moves policy information from a custom field to the header for revisions.

Test Plan: Looked at a revision.

Reviewers: btrahan, chad

Reviewed By: chad

CC: aran

Maniphest Tasks: T603

Differential Revision: https://secure.phabricator.com/D7135