Bring in jsfiddle integration script, add harmony

Brings in http://dragon.ak.fbcdn.net/hphotos-ak-prn1/851561_341095626017279_6573_n.js which is currently living at http://fb.me/react-js-fiddle-integration.js. We should just serve from GitHub for this so its easier to update. In fact we can skip the fb.me hop entirely and update the base fiddle to point at facebook.github.io/js/jsfiddle-integration.js

cc @vjeux 
Nope, we made it strict in #1827.