Design V2 for auth0-guardian-js

This version aims to solve the issues associated with state and
event handling for Guardian Widget so we can reduce its complexity
and people will be able to build their own versions of it.

Main concepts:
- The library should work both client and server side
- We should reduce the ammount of dependencies
- Transactions management should be isomorphic for all factors.
- Enrollment should be isomorphic for all factors
- We should hide the details of the old api (names, etc) and translate the concepts to the new one.
- We should be able to easily mock great part of it
- It should support all factors for Guardian JS
- There should be a working example