Setup a default discovery method

[ignasi35]

Should akka.discovery.method = akka-dns be a default in lagom-akka-discovery-service-locator?

If it's going to set a default [...] the best default to use would be aggregate preconfigured with both config and DNS (in that order of priority). That makes it really easy to plug in manual configuration to override DNS entries or add ones that aren't available in DNS.

Originally posted by @TimMoore in lagom/online-auction-java#213 (comment)

[ihostage]

👍
My first step of upgrade service to 1.5.0 is adding akka.discovery.method = akka-dns to production.conf. I will be happy if I can miss this step. 😂

[octonato]

+1 for aggregate = [ config, dns ]