Don't allow logout for the anonymous demo

demo/anonymous.html

@@ -52,6 +52,7 @@
 <script>
     require(['converse'], function (converse) {
         converse.initialize({
+            allow_logout: false, // No point in logging out when we have auto_login as true.
             allow_muc_invitations: false, // Doesn't make sense to allow because only
                                           // roster contacts can be invited
             allow_contact_requests: false, // Contacts from other servers cannot,