Basic remarkup integration for Phriction
Summary: Document linking and some general layout improvements. I'd like to
eventually do more meta-dataey things with links (like store them separately and
check them for 404s) but this is a decent start.
Test Plan:
https://secure.phabricator.com/file/view/PHID-FILE-d756b94a06b69c273fce/
Reviewed By: jungejason
Reviewers: hsb, codeblock, jungejason, tuomaspelkonen, aran
CC: aran, jungejason, epriestley
Differential Revision: 650