Handling Anon users

[craigmulligan]

I want to use this module for our websites to track page views and other events, but currently .start() requires a user obj.

I'm thinking we generate a uuid if no user object is passed, and then not run the login event. I see a lot methods depend on the properties that are set in the login method like distinctId so we will may have to have an alternative like anonLogin for add a conditional to the login so to not create a new Person in mixpanel for every new page visit.

What do you think? @pimterry @emirotin

[emirotin]

Makes sense to have a separate method
In general, mixpanel is already capable of handling anons, we just need to relax the assumptions this module puts on the authentication model.