Loaded editor locally and added polyfill (#114)
Notes:
 - editorLoader.js will automatically load watever scripts are in editor.html as a data url to conserve bandwidth
 - I added message_channel.js for a polyfill until firefox implements it.
 - I had to change the file a little because of problems with the latest version of firefox and to allow for domain checking
     (see: https://github.com/tildeio/MessageChannel.js/issues/18)