use env var INSTANCE_DIR for run script

run-httpd.sh

@@ -8,7 +8,7 @@ WORKER_TIMEOUT=${WORKER_TIMEOUT:=120}
 
 if [[ "$DEBUG" = true ]] ; then
     echo "Running manage.py runserver"
-    python3 /var/www/pvs/dev/pvs_instance/manage.py runserver 0.0.0.0:80
+    python3 "$INSTANCE_DIR"/manage.py runserver 0.0.0.0:80
 else
     echo "Running gunicorn"
     exec \