Fix top margin on infoview + two-column

Summary: When you save settings or don't have reviewers, we show an info box inside an object box. This rule is squashing the margin. Blame seems to indicate I added it for Differential updates, but in re-visiting Differential, I'm unable to trigger any broken CSS with this change. But keep an eye out?

Test Plan: Badges, Settings, Differential

Reviewers: epriestley

Reviewed By: epriestley

Subscribers: Korvin

Differential Revision: https://secure.phabricator.com/D15992