R1:965a4da042d0

Add a "jump nav" element to the homepage, for quick tool/object navigation

Summary:
- Restore quick methods for getting to common features (upload file, create
task, etc.)
- Provide a flexible cli-like navigation element similar to stuff used at
Facebook (bunny1 / lolbunny).

Test Plan: Used jump nav and nav buttons.

Reviewers: btrahan, fratrik

Reviewed By: btrahan

CC: aran, epriestley

Differential Revision: https://secure.phabricator.com/D1619