R1:92ee3e764253

Add basic grey and blue styles for PHUIBoxView

Summary: We plan to use these more in future mocks. Adds base colors and re-uses in Phame.

Test Plan: Phame, mobile and desktop.

Reviewers: epriestley

Reviewed By: epriestley

Subscribers: Korvin

Differential Revision: https://secure.phabricator.com/D15069