Reduce number of emails for staff

Staff currently get four simultaneous emails when added the AnthroCon
way. This prevents the extraneous emails from getting sent.
Not sure if this is the case for master, but basically, AnthroCon is using groups in a unique way - to set up staffers with badges.

That means a lot of groups that don't owe any money, which means this email was getting sent to the first staffer who registered. Each staffer was getting about 4 simultaneous emails total, which is why I made these changes. :)