Merge: nitcorn: redirect requests of directories to an URI ending with '/'

Example: request sent to http://xymus.net/nit will be redirected to http://xymus.net/nit/ (xymus.net) has not been updated yet). It fixes the loading of other assets such as css files.

Pull-Request: #751
Reviewed-by: Lucas Bajolet <r4pass@hotmail.com>
Reviewed-by: Jean Privat <jean@pryen.org>
Reviewed-by: Alexandre Terrasa <alexandre@moz-code.org>