Added support do do a push-state ajax request with forms

lib/proto/parse-element.js

@@ -7,8 +7,11 @@ module.exports = function(el) {
     }
     break
 
-  case "form":
-    throw "Pjax doesnt support <form> yet."
+    case "form":
+      // only attach link if el does not already have link attached
+      if (!el.hasAttribute('data-pjax-click-state')) {
+        this.attachForm(el)
+      }
     break
 
   default: