Clean up UI a little.

Summary: Mainly this changes the fonts and some minor navigation colors. I wanted to get rid of some of the 'girly blues' from Facebook and mute everything a little bit to match the change to Helvetica and new buttons.

Test Plan: Tested Manifest, Profiles, and other random pages I could find. Single and Multiple Navigations. http://phab1.pushlabs.net/

Reviewers: epriestley, btrahan

Reviewed By: btrahan

CC: vrana, aran, Korvin

Differential Revision: https://secure.phabricator.com/D3955