Make sure nodes not supporting signing informs GW

A node that does not support signing, still needs to inform the
gateway about this to make sure the gateway carries a valid signing
requirement table when a node Id that was requiering signing stops
doing this.
This fixes arduino#286.

Author: fallberg

libraries/MySensors/core/MyTransport.cpp

@@ -553,6 +553,9 @@ void transportPresentNode() {
 				#else
 					_sendRoute(build(_msg, _nc.nodeId, GATEWAY_ADDRESS, NODE_SENSOR_ID, C_INTERNAL, I_REQUEST_SIGNING, false).set(false));
 				#endif
+			#else
+				// We do not support signing, make sure gateway knows this
+				_sendRoute(build(_msg, _nc.nodeId, GATEWAY_ADDRESS, NODE_SENSOR_ID, C_INTERNAL, I_REQUEST_SIGNING, false).set(false));
 			#endif
 
 			// Send presentation for this radio node