Filtering users by type to avoid clutter

[skeltont]

Currently in the admin interface for viewing users you're able to see all of the users of every type. Over time, if we get a lot of outside registrations, that list could get unwieldy.

IDEA: put a checkbox, or radio, next to the search box that's like "include public users" and then search will cover all users in the db. However, on first load we won't load any public users and only list users that are pertinent to gym activity (setters and up).