add * for required fields

Resources/public/css/layout.css

@@ -85,4 +85,10 @@ em.sonata-ba-field-help {
     display: block;
     color: #999;
     margin-bottom: 10px;
+}
+.required{
+    color:red;
+}
+.required:after{
+  content:"*";
 }