fix JSFiddle

"External Resources" had a bad rawgit.com URL.  Fixed to v0.4.0.
Sorry I didn't want to plaster my namespace over yours; but it will help if I need to re-edit, like if my suggestion for [shorter version URL is used](https://github.com/ractivejs/cdn.ractivejs.org/issues/1).  Feel free to re-fork to reclaim.