Add support for bookmarks in Phabricator emails.

Summary: Right now emails don't include bookmark info (wasn't added in D2897). Lets include it so it's consistent with the web UI.

Test Plan: Inspected code, made sure it matched web UI code. Verified that web UI with these changes was consistent with rendering before refactoring.

Reviewers: epriestley

Reviewed By: epriestley

CC: Korvin, aran

Differential Revision: https://secure.phabricator.com/D7215