COOK-1460 Don't generate the ports.conf twice with mod_ssl

When using apache2::mod_ssl, the ports.conf was generated twice causing a restart of Apache on every Chef run. This fixes the issue.

Additionally, it allows to configure the added SSL port for those uncommon (but common enough) setups where it is necessary (e.g. because another component like a loadbalancer is already bound to 0.0.0.0:443).