XHR now has a close method

lib/transports/xhr.js

@@ -130,6 +130,18 @@
 
     this.sendXHR.send(data);
   };
+  
+  /**
+   * Disconnects the established `XHR` connection.
+   *
+   * @returns {Transport} 
+   * @api public
+   */
+
+  XHR.prototype.close = function () {
+    this.onClose();
+    return this;
+  };
 
   /**
    * Handle the disconnect request.