Interim commit for refactoring out web-centric logic.
* Use SubscriptionEvent to handle the sending of the welcome message. * Use ConfirmationNeededEvent to send the confirmation message. * For now, hard code the adminurl and comment out the listinfo_uri. * Pend the list-id instead of the fqdn-listname * Use the new configuration support for Postfix settings. * Get rid of the IDomain's url_host, base_url, and scheme attributes, as well as the confirm_url() method. * Get rid of the IMailingList's script_url() method.