Remove consumed invitations when deleting an invitee account.
This commit takes care of deleting the invitation consumed by an invitee account when this is deleted. This allows the Family pack owner to create a new invitation.
Due to an influx of spam, we have had to impose restrictions on new accounts. Please see this wiki page for instructions on how to get full permissions. Sorry for the inconvenience.
This commit takes care of deleting the invitation consumed by an invitee account when this is deleted. This allows the Family pack owner to create a new invitation.