Author merging

[carboxylman]

We probably want to allow users to link/merge their person to/with artifactaffiliation persons. Exactly how we do this might be a question, but something that we want to support. We ideally want some kind of automatically verifiable proof, but this is pretty hard in practice. If author/user match on email/institution, decision is easy; but if only name, and if name is fuzzy, we might have to just allow this nearly unverified, and intervene if there is a challenge from another user.