R1:4bf559baa01c

Add a script to programmatically add image macros

Summary: Urgent request.

Test Plan: Ran "add_macro.php" on some things; verified results in web console.

Reviewers: btrahan, tcook

Reviewed By: btrahan

CC: aran, epriestley

Differential Revision: https://secure.phabricator.com/D1832