load JS from http://rawgithub.com/ instead of https://raw.github.com/

The javascript files hosted on `raw.github.com` have a content-type of `text/plain`, this, along with the header `X-Content-Type-Options: nosniff` from Github, prevents Chrome from parsing the scripts as javascript.  This is because of Chrome's strict MIME-type parsing, see:

http://i.imgur.com/UD1WdS4.png
https://plus.google.com/+MikeWest/posts/28f8HS2M7cb
https://code.google.com/p/chromium/issues/detail?id=180007