added RichRatingsFor{Flight,Route}

{departure,arrival}AirportFsCode changed from String -> Option[String]
split FlightAppendixHelper into FlightAppendixHelper & CarrierAppendixHelper
  (some response types have {departure,arrival}AirportFsCode but don't
  agree on carrierFsCode vs. airlineFsCode)
cleaned up names still using promise in api.v1.pakage
cleaned up "async" testing