SLO not working after upgrade to IdP v5

[Cantor, Scott]

> I tested 5.2 and it showed another error:

Thanks for testing it, I'm not shocked, I think there will be a handful of issues. It just didn't get tested at all for the releases.

> OK, I'll follow your recommendation and drop the SOAP
> logout.

I'm all but certain we'll deprecate that and the inbound artifact support (not outbound) ahead of 6.0, and those are the main use cases for that client right now. The SP isn't going to support the reciprocal features in the future, so syncing that up is my intention.

-- Scott