Subscribe l2gw agent to neutron conf changes

Change-Id: Ie0401bab6b2ed6551c47b90084c03c1fd960447c
diff --git a/neutron/agents/l2gw.sls b/neutron/agents/l2gw.sls
index e55ad3b..53e048a 100644
--- a/neutron/agents/l2gw.sls
+++ b/neutron/agents/l2gw.sls
@@ -26,6 +26,7 @@
   - enable: true
   - watch:
     - file: /etc/neutron/l2gateway_agent.ini
+    - file: /etc/neutron/neutron.conf
 
 {%- endif %}
 {%- endif %}