Fix radio buttons display

That was broken by Django 1.11 upgrade

Bug was introduced in 9b6c7dcc2830c3824e247b984acab77b5988743d

wifiwithme/apps/contribmap/templates/contribmap/wifi-form.html

@@ -62,8 +62,8 @@
 
     <h3>Type de connexion</h3>
     <div id="id_access_type">
-      {% for i in form.access_type %}
-      {% if i.choice_value %}<p class="radio">{{ i }}</p>{% endif %}
+      {% for i in form.access_type.subwidgets %}
+        {% if i.data.value %}<p class="radio">{{ i }}</p>{% endif %}
       {% endfor %}
     </div>