As an admin, I want to subscribe user groups to pages for group email notifications

The feature would allow confluence admins to assign an email address to a group (whether that group comes from the internal directory, from Crowd, or from LDAP) and then allow the group to be subscribed to a page.

Essentially this would mean we could subscribe a group to a page without creating a dummy account, which in most organisations would be otherwise a wasted user account adding towards the license limit.