Store user badge names per-event #31
Description
Currently, a user's badge name is always overwritten with the latest one provided by ConCat. The badge name is part of the registration for an event in ConCat, and can thus be different between events. Tracker should store them associated with their appropriate event and display the badge name for users from the event that's being viewed. When there isn't an event to look at, we should just fall back to the user's username.