Start a new HTTP server.
the TCP port used. If set to 0, it starts on any available port. This is the default.
the ip address this server listen at. 0.0.0.0 means listening on all available address. This is the default.
if provided, the SSL configuration to use. In this case the server will listen for HTTPS requests.
scala.concurrent.ExecutionContext to use to run user code.
a server instance that you can stop later.