Re: Introduce contributor badges

Re: Magnus Hagander
> Given the fairly substantial concerns raised ofer this during in-person
> discussions at FOSDEM, please do *not* commit this until you have signoff
> from those involved. (It might be that it's fine, but given the concerns
> and discussions around it, let's make sure those are resolved).

I said in the other thread:

> The last result (from the lunch discussion in Brussels) was that we
> need handling of retired people from "permanent" badges like "Sysadmin
> Team". That's not included yet, but in the team, we concluded that
> instead of some complicated date range handling (perhaps that's what
> you remember as plenty?) we can just add a single boolean "retired"
> flag. We don't have that yet, but that's not a big blocker.

I've now implemented retiring from badges. Internally it's tracked by
filling in a date_retired field, but in order not to overcomplicate
the user interface, it's treated as a boolean. Retirees still show up
in badge listing, but are marked as retired.

Removing people from badges is now a two-stage process, retire them
and then remove them. To un-retire someone, add their email address
again (which NULLs the date_retired field).

I'm attaching that as a separate commit for better review. It would
get squashed before committing, of course.

I believe that addresses the concerns from Brussels, or was there
anything else?

Christoph