ReplyTo EPR must be manually reset after Aggregator action is used

Any ReplyTo EPR which was present on incoming messages to the Aggregator was not being propagated to the aggregated message. As a result it was necessary to explicitly set the EPR using a pipeline action after the aggregator. Now, if the same EPR is present on each of the incoming messages to the aggregator then that EPR will be propagated to the aggregated message.