Use a simpler footer style to accommodate overly wide pages
Summary: Not really thrilled about my fix for T684 in D1224. This makes some
design tweaks to solve it without the awkward horizontal scrollbar in the page
content div.
Test Plan: Looked at diffs overflowing the window. Looked at footer on several
pages.
Reviewers: btrahan, jungejason, Makinde
Reviewed By: btrahan
CC: aran, btrahan
Maniphest Tasks: T684
Differential Revision: https://secure.phabricator.com/D1332