R1:626b6a7f970c

Add 24px and 48 loading graphics.

Summary: Fixes T3156 - Adds nautical loading indicators.

Test Plan: Photoshop

Reviewers: epriestley, btrahan

Reviewed By: btrahan

CC: aran, Korvin

Maniphest Tasks: T3156

Differential Revision: https://secure.phabricator.com/D5905