get protocol from headers['X-Scheme'] ,
I can't get 'https' from request.protocol
as tornado doc mentioned "The protocol used, either “http” or “https”. If HTTPServer.xheaders is set, will pass along the protocol used by a load balancer if reported via an X-Scheme header."

https://www.tornadoweb.org/en/stable/httpserver.html?highlight=protocol#tornado.httpserver.HTTPRequest.protocol
add travis-ci job link