Update reference architecture to use the new ECS Service Discovery capability

[luispollo]

With the announcement of the new built-in Service Discovery capability in ECS (which relies on Route53 Autonaming) at AWS re:Invent 2017, it would be nice to revisit this reference architecture using that mechanism, which would simplify the architecture (in particular, removing the need for the Lambda functions). Once it becomes generally available, of course. :-)

http://docs.aws.amazon.com/Route53/latest/APIReference/overview-service-discovery.html

[dsouzajude]

+1