code: function SpineLoader(url, crossorigin)
  {
      EventTarget.call(this);
  
      /**
       * The url of the bitmap font data
       *
       * @property url
       * @type String
       */
      this.url = url;
  
      /**
       * Whether the requests should be treated as cross origin
       *
       * @property crossorigin
       * @type Boolean
       */
      this.crossorigin = crossorigin;
  
      /**
       * [read-only] Whether the data has loaded yet
       *
       * @property loaded
       * @type Boolean
       * @readOnly
       */
      this.loaded = false;
  }
docs: The Spine loader is used to load in JSON spine data
  To generate the data you need to use http://esotericsoftware.com/ and export the "JSON" format
  Due to a clash of names  You will need to change the extension of the spine file from *.json to *.anim for it to load
  See example 12 (http://www.goodboydigital.com/pixijs/examples/12/) to see a working example and check out the source
  You will need to generate a sprite sheet to accompany the spine data
  When loaded this class will dispatch a "loaded" event
  
  @class Spine
  @uses EventTarget
  @constructor
  @param url {String} The url of the JSON file
  @param crossorigin {Boolean} Whether requests should be treated as crossorigin