Use for=ID on radio/checkbox label.

This is required for some screen reader like Jaws

src/Symfony/Bridge/Twig/Resources/views/Form/bootstrap_3_layout.html.twig

@@ -148,10 +148,14 @@
 {% endblock %}
 
 {% block checkbox_label -%}
+    {%- set label_attr = label_attr|merge({'for': id}) -%}
+
     {{- block('checkbox_radio_label') -}}
 {%- endblock checkbox_label %}
 
 {% block radio_label -%}
+    {%- set label_attr = label_attr|merge({'for': id}) -%}
+
     {{- block('checkbox_radio_label') -}}
 {%- endblock radio_label %}