validate remote HTTP Request
send HTTP 400 Bad Request for invalid HTTP Request
add static files and a PHP scripts in htdocs
reuse address and port, and get rid of error: "unable to bind, address already in use"
add adminsitrative URI to stop server
support static files and HTTP GET Method
remove admonistrative URI to shutdown server. shutdown via Ctrl+C is 0kay now
remove "It's Works" as default response body
support PHP scripts