API koa middleware

"Add the middleware in order"

1. param_parser : parse the incoming request parameter json/xml and re-assign to request body.
2. error_handler : handle exception error or throwed error each middleware through downstream middleware.
3. request_logger : contruct message content of request and its response content.
   • listener : create event listener for 'error' and 'logger' and log/console log the content.
   • request : add to the end middleware of router to log the request and its response content "must add next()".