Enable gzip and use laravel error_page for php files

[benbrummer]

1. Activate gzip as described in the documentation https://invoiceninja.github.io/en/self-host-installation/
2. Set error_page as described in the laravel documentation https://laravel.com/docs/master/deployment#nginx. try_files $uri =404;will catch e.g https://example.com/some_file.php