Extending ng-model functionality to hidden fields

Hidden fields are still used in hybrid solutions such as MVC.net/etc. and it is valuable to be able to set value of this type of field through ng-model.

Author: stsvilik

src/ng/directive/input.js

@@ -375,7 +375,7 @@ var inputType = {
    */
   'checkbox': checkboxInputType,
 
-  'hidden': noop,
+  'hidden': textInputType,
   'button': noop,
   'submit': noop,
   'reset': noop