fix(form): refresh on instance to fetch dom changes

When a form gets initialized it is refreshing the field selectors.
This is fine as long as there is only one call to the same form. Whenever a later bahavior call like get values takes place on the same form and the form fields have changed, the previous stored instance is not getting refresh (because only the "new" module is)

Author: lubber-de

src/definitions/behaviors/form.js

@@ -627,7 +627,7 @@ $.fn.form = function(parameters) {
             instance = $module.data(moduleNamespace);
 
             // refresh selector cache
-            module.refresh();
+            (instance || module).refresh();
           },
           field: function(identifier) {
             module.verbose('Finding field with identifier', identifier);