set default value for mandrill_groups_og_ref field based on value from URL if it is present
remove "administer mandrill groups inbound domains" permission and use "administer mandrill" instead. reason being functionality exposed on page that used the previous permission in its access callback modifies things in the authenticated mandrill account so it makes sense to have the permissions match those to administer mandrill
remove mandrill_groups_og_ref field from discussion node form if user does not have "administer mandrill discussion group" permission