Temporary store `to` property

[Swaagie]

Temporary store the to property in Redis so account creation for instance can be deferred until after validation of the email/sms or similar. This property should also be returned as third argument in the validate callback.

[3rd-Eden]

So what i'm suggesting here is to completely remove the id requirement which only made sense when you create accounts before login and start storing all the data that is passed in the login method: https://github.com/observing/tolkien#tolkienlogin in dynamis directly so when we do https://github.com/observing/tolkien#tolkienvalidate we can merge this stored data with the third argument.

Removing the id also clean ups the code a bit further as we can just nuke the part where store the id->token relations https://github.com/observing/tolkien/blob/master/index.js#L151-L156