added support for mod_fastcgi

when using mod_fastcgi SCRIPT_NAME is the Action instead of the actual document you want
this commit uses PATH_TRANSLATED - DOCUMENT_ROOT

tested with:
apache+mod_fastcgi
apache+mod_proxy_fcgi
nginx with no PATH_TRANSLATED header
nginx with this as PATH_TRANSLATED: fastcgi_param  PATH_TRANSLATED    $document_root$fastcgi_script_name;