Add X-Accel-Redirect support for Nginx (a sibiling of X-Sendfile)

For it to work you have to modify your nginx conf to send X-Accel-Mapping header using
-> proxy_set_header X-Accel-Mapping /var/www/ajaxplorer/data/=/data/;
or
-> fastcgi_param X-Accel-Mapping /var/www/ajaxplorer/data/=/data/;
and you have to use the "internal" keyword
-> location ~ /data/ { internal; }

The X-Accel-Mapping idea come from the rails world
Merge pull request #240 from echampet/xaccel

Add X-Accel-Redirect support for Nginx (a sibiling of X-Sendfile).