consistency in twig methods

The method chill_custom_fields_is_empty take now the fields as first argument, and the customField as second argument, to be consistent with other twig methods.

Templating/Twig/CustomFieldRenderingTwig.php

@@ -85,7 +85,7 @@ class CustomFieldRenderingTwig extends \Twig_Extension implements ContainerAware
     }
     
     
-    public function isEmptyValue(CustomField $customField, $fields, $slug = null)
+    public function isEmptyValue($fields, CustomField $customField)
     {
         return $this->container->get('chill.custom_field.helper')
             ->isEmptyValue($fields, $customField);