Style quote reply headers

Summary: Adds some minor tweaks to the Quoted Remarkup rules. I tried altering the nested quote as well, but it became a bit of a joke quickly, not sure there is benefit there. Fixes T4962

Test Plan:
Quoted lots of times.

Reviewers: epriestley

Reviewed By: epriestley

Subscribers: epriestley, Korvin

Maniphest Tasks: T4962

Differential Revision: https://secure.phabricator.com/D9502