Web interface to groups/format_groups.py

[adehnert]

We have a script, groups/format_groups.py, which formats the list of groups in various ways (for inclusion in web forms --- see #173; for updating finboard-groups-only@; etc.). Some of these saved to a file in the locker regularly. For those that aren't, and in cases where a bunch of groups' DB entries are changed and an updated list is required quickly, it would be nice to have a page in the DB that let you pick one of these lists and view it immediately on the site.