To complete solid/solid#14, we need to record what to do with incoming requests after deletion. At the very least, we should make sure that nobody gets the same URI so that they can impersonate the former account owner.

As noted there, we should respond with 410 if nothing else has been recorded, but even better is it to allow users to register their new home and do a 301. At the very least, their new WebID should be saved.

I thought about using the old .htaccess format for this, that we just dump such a file in the former home dir of the user.