Remember token not set for impersonated user

#71 Saved the impersonator's remember me token to session and re-created the cookie when leaving impersonation. That works great. The only thing not solved now is creating a remember me token for the user you're impersonating. If your session expires while impersonating you'll simply be logged out.

It would be nice if, while impersonating, and your session expires, you would be logged back in as the impersonator impersonating. Of course the remember me token should only be created if the impersonator has one.