added 502 error page

gliders.nginx.conf

@@ -45,6 +45,11 @@ server {
         try_files $uri @rewriteapp;
     }
 
+    error_page 502 /502.html;
+    location @error_502 {
+        rewrite ^(.*)$ /502.html break;
+    }
+
     error_page 503 @maintenance;
     location @maintenance {
         rewrite ^(.*)$ /maintenance.html break;
@@ -84,7 +89,7 @@ server {
     location ~ ^/(app|app_dev|config)\.php(/|$) {
         fastcgi_pass hhvmfcgi;
         fastcgi_intercept_errors on;
-        # error_page 502 = @fallback;
+        error_page 502 = @fallback;
         include fastcgi_params;
         fastcgi_split_path_info ^(.+\.php)(/.*)$;
         fastcgi_param  SCRIPT_FILENAME $symfonyroot/web$fastcgi_script_name;