Added the HTTPS fastcgi_param to fastcgi.conf.

conf/fastcgi.conf

diff --git a/conf/fastcgi.conf b/conf/fastcgi.conf
index fab09eb..ac9ff92 100644
--- a/conf/fastcgi.conf
+++ b/conf/fastcgi.conf
@@ -10,6 +10,7 @@
 fastcgi_param  DOCUMENT_URI       $document_uri;
 fastcgi_param  DOCUMENT_ROOT      $document_root;
 fastcgi_param  SERVER_PROTOCOL    $server_protocol;
+fastcgi_param  HTTPS              $https if_not_empty;
 
 fastcgi_param  GATEWAY_INTERFACE  CGI/1.1;
 fastcgi_param  SERVER_SOFTWARE    nginx/$nginx_version;