Implement very basic uberhome

Summary:
No fancy-pants smarty stuff yet, but merges /applications/ and the awful application buttons into the dark navigation.

Hover state is maybe a little weird.

Test Plan: {F29324}

Reviewers: chad, btrahan

Reviewed By: btrahan

CC: aran, btrahan, codeblock

Differential Revision: https://secure.phabricator.com/D4431