Use exec to start supervisord for graceful shutdown

- Ensures `supervisord` receives termination signals by making it PID 1

Author: Revisto

docker/docker-entrypoint.sh

@@ -32,4 +32,4 @@ rm -r /var/www
 ln -s $(pwd)/site /var/www
 
 # Start services
-/usr/bin/supervisord -c /etc/supervisord.conf
+exec /usr/bin/supervisord -c /etc/supervisord.conf