ReceivingEndpoint to check NServiceBus.FailedQ header only
Added intent to sagahistory message flows

So now InitiatingMessage has an extra property called Intent
Also each OutgoingMessages has an extra property called Intent

Intent can be:
* "Send", regular point-to-point send
* "Reply", a message reply (this one at the moment is broken, see https://github.com/NServiceBus/NServiceBus/issues/1409)
* "Publish", a one-to-many sends to subscribers