xDiffs and Revisions Generating

Summary: Ref T2903

Test Plan: Revisions and Diffs are visually being generated

Reviewers: epriestley, xask.linus

Reviewed By: epriestley

CC: AnhNhan, aran, Korvin

Maniphest Tasks: T2903

Differential Revision: https://secure.phabricator.com/D5835