Make sure auth module listens for current-user deletion

@aweiksnar That issue you had with the failing tests might not have been entirely cookie-related. I wasn't going through the sign-out business when the current account was deleted, so the auth module was left in a weird state of having a currentUser that didn't exist and a revoked bearer token. This fixes that.
I think this is what is causing the page to falsely render as though not signed-in--changing it back to null seems to make things behave as normal