(stable) Stick the page footer in the right place on Formation View pages

Summary: Ref T13516. This isn't terribly clean, but get the page footer into the bottom of the content page on FormationView pages so it doesn't overlap into the side panel.

Test Plan: With and without a footer, viewed normal and FormationView pages. Saw footers in appropriate places at appropriate times.

Maniphest Tasks: T13516

Differential Revision: https://secure.phabricator.com/D21166