switches the fileupload required property on if data-required is set to yes

javascript/src/QfqForm.js

@@ -395,6 +395,10 @@ var QfqNS = QfqNS || {};
         $inputFile.prop("disabled", false);
         $inputFile.removeClass('hidden');
 
+        if ($inputFile.data('required')=='yes') {
+            $inputFile.prop("required", true);
+        }
+
         $inputFile.val("");
 
         this.form.markChanged();