Add TCP abstractions to spring-messaging

This change adds abstractions for opening and managing TCP connections
primarily for use with the STOMP broker support. As one immediate
benefit the change makes the  StompBrokerRelayMessageHandler more
easy to test.

spring-messaging/src/main/java/org/springframework/messaging/MessageDeliveryException.java

@@ -37,6 +37,10 @@ public MessageDeliveryException(Message<?> undeliveredMessage, String descriptio
 		super(undeliveredMessage, description);
 	}
 
+	public MessageDeliveryException(Message<?> message, Throwable cause) {
+		super(message, cause);
+	}
+
 	public MessageDeliveryException(Message<?> undeliveredMessage, String description, Throwable cause) {
 		super(undeliveredMessage, description, cause);
 	}