search for request_uri in try_files

this lets us put images in app_not_responding.html

src/nginxconfig.ejs

@@ -132,7 +132,7 @@ server {
     location /app_error_page {
         root /home/yellowtent/boxdata;
         # the first argument looks for file under the root
-        try_files /custom_pages/app_not_responding.html /appstatus.html;
+        try_files /custom_pages/$request_uri /custom_pages/app_not_responding.html /appstatus.html;
         # internal means this is for internal routing and cannot be accessed as URL from browser
         internal;
     }