R1:7ac5cd762830

Minor tweaks to Maniphest

Summary: A bit better spacing on tasks and matching the styles of Differential. Should help normalize the homepage.

Test Plan: Review a list of tasks, fake some data.

Reviewers: epriestley, btrahan

Reviewed By: epriestley

CC: aran, Korvin

Differential Revision: https://secure.phabricator.com/D4487