The ability to remove / discontinue a badge

[ryanlerch]

There are some badges that are "discontinued", i.e. they are not able to ever be earned again. It would be nice to be able to mark this in the UI

there are really two classes of badges that this happens to, and we might want to treat them differently:

1. Event badges, like Flock badges -- these are specific to an event, and if the event is over, noone can ever earn that badge again.
2. things change. For example, FAS2 used to broadcast on Fedora Messaging when a user changed their password. We don't do this anymore in Noggin, so the user changed their password badge can never be earned again.

[abompard]

I see two other use cases:
3. Badges that we've decided to remove completely and that should no longer appear on people's profiles, for any reason (it was a bad idea, it was offensive and we've learnt to do better, it's no longer something we want to encourage, etc)
4. Badges we want to temporarily disable. For example we have disabled the Copr badges because the amount of Copr build has drastically increased and the badges system was no longer capable of handling the load. We might bring them back again when we figure out a way to solve the load issue, but in the meantime they are "on hold" somehow.

[abompard]

I think we could add fields to the Yaml spec and to the database table, and then find a way to display that in the UI.
Note that we should also add a last_modified column to that table so that the consumer (fedbadges) knows when to reload its ruleset.