Add a common interface and finagle-based implementation for an http client. #472

• Simplify Retryer (=> RetryContext) to support http error handling airframe-control: Remove context from Control.Retrier #467 Retryer -> RetryContext #491
• Add HttpStatus code representations using type classes (xxxAdapter)
• Add a standard HTTP response hander Add a basic retry pattern set for HTTP requests #366
• Add a finagle-based HTTP client
• Add async/sync http clients. Using F[_] as an abstraction of Future. This is useful to remove the dependency to Finagle in airframe-http.
• Support circuit breaker (No code for this. We can use circuit breaker of Finagle by customizing FinagleClientConfig.initClient)
• Integrate control.Retry and FinagleRetryFilter.
  • Finagle will not enable request retry by default, so we anyway need to add our own retry filter.
  • Simplified control.Retry so that we can use this retry logic both for imperative programming and Future-based programming.
• Support response/request -> object mapping with airframe-codec.