New Methods in v1.2, minor additon to WebHooks

[jesse]

As listed in the changelog : http://www.mailchimp.com/api/changelog.php

* Webhooks: start including the list_id for every callback
* MailChimp API v.1.2.1 release
** add the listWebhooks(), listWebhookAdd(), and listWebhookDel()
methods to the API

Those using the PHP MCAPI wrapper will need to grab a new copy from
the downloads page to use the new functions:
http://www.mailchimp.com/api/downloads/