_cacheBust = function(path, options) {
    var cacheBust = options == null || options && options.cacheBust === true;
    if (cacheBust) {
      return (path.indexOf("?") === -1 ? "?" : "&") + "noCache=" + _now();
    } else {
      return "";
    }
  }
Will look at a path, and will create a "?noCache={time}" or "&noCache={time}"
query param string to return. Does NOT append that string to the original path.
This is useful because ExternalInterface often breaks when a Flash SWF is cached.

@returns The `noCache` query param with necessary "?"/"&" prefix.
@private