refactor to use nginx includes more

[naggie]

Now that variables can be used in https certificate paths

https://nginx.org/en/docs/http/ngx_http_ssl_module.html#ssl_certificate

ssl_certificate     $ssl_server_name.crt;
ssl_certificate_key $ssl_server_name.key;

This could allow use without ansible, too. A single file for many hosts could be used.