Send 404 when nothing server at '/'

Prevents Nginx welcome screen

core/nginx/conf/nginx.conf

@@ -91,6 +91,8 @@ http {
       location / {
         return 301 {{ WEBROOT_REDIRECT }};
       }
+      {% else %}
+        return 404
       {% endif %}
 
       {% if WEBMAIL != 'none' %}