guipe

Remove default config for smtpd_tls_cert_file and smtpd_tls_key_file to avoid warning message in logs

1

When TLS is not used, if we let default configuration: ``` smtpd_tls_cert_file=/etc/ssl/certs/ssl-cert-snakeoil.pem smtpd_tls_key_file=/etc/ssl/private/ssl-cert-snakeoil.key ``` These warning messages appears in /var/log/maillog: ``` Jul 29 14:24:01 postfix/smtpd[24123]: warning: cannot get RSA certificate...