attach data to pjaxified links so they can't be pjaxified twice. add simple refresh method

lib/proto/attach-link.js

@@ -56,6 +56,8 @@ var linkAction = function(el, event) {
 module.exports = function(el) {
   var that = this
 
+  el.setAttribute("data-pjax-enabled", "true");
+
   on(el, "click", function(event) {
     linkAction.call(that, el, event)
   })