Summary: Adds a basic div box that takes some styles. Not sure this is the best approach for the spacing, but overall hoping people can spend less time in CSS and just use this class.
Test Plan: UIExamples
Reviewers: epriestley, btrahan
Reviewed By: epriestley
CC: aran, Korvin, AnhNhan
Differential Revision: https://secure.phabricator.com/D5723
