Fix a bug

Fix a bug which occurs when an `asset.directory` is declared and starts by "./web" or just by the name as example "web/", and if the css is called from an url which doesn't start by the base root as example "http://website.com/page/user".
The asset path was "http://website.com/page/user/web/css/custom.css" and not "http://website.com/web/css/custom.css".