differential - lazy man's attempt at updated design

Summary: basically made the header elements for the individual panes and cleaned up the panes to make it look okay. tried to copy colors from @chad 's mocks.

Test Plan: looks good to me

Reviewers: epriestley, chad

Reviewed By: chad

CC: aran, Korvin

Maniphest Tasks: T2004

Differential Revision: https://secure.phabricator.com/D4174