Reload DNS config also on ifdown (e.g. after closing a vpn tunnel)

src/net/java/sip/communicator/impl/dns/DnsUtilActivator.java

@@ -147,6 +147,7 @@ private static class NetworkListener
         public void configurationChanged(ChangeEvent event)
         {
             if((event.getType() == ChangeEvent.IFACE_UP
+                || event.getType() == ChangeEvent.IFACE_DOWN
                 || event.getType() == ChangeEvent.DNS_CHANGE)
                 && !event.isInitial())
             {