Logging in should revoke existing token if any

[rauchg]

If we're logging out to log in under a different account, we should revoke the existing token.

[leo]

Here's an example of how we're revoking the token in Now.app.

[codyzu]

Looks like Now.app revokes the token by calling:
DELETE: https://zeit.co/api/www/user/tokens/{tokenId}

What is the api call for now? Will this work?
DELETE: https://api.zeit.co/now/registration/{token}

@leo can you confirm on the server side what the api call should be?

[codyzu]

Looking through old issues... @leo any update on this?

[leo]

Yep, that's how it should be done. Not sure if he's talking about deleting the token from ~/.now.json or about revoking it through the API. Can you test that, @codyzu? If the former is already the case, then the latter needs to follow.

[codyzu]

@leo ok I'll try to take a look tomorrow.