Make IdentityManager a factory and nothing else.

[aliak00]

Currently it stores its own currentUser object. This should just be created and given back to the client in a callback after any of the "login" related functions, i.e.:

• verify code
• login with username and password

Suggested approach

1. Create the new functions
2. deprecate currentUser and the old functions
3. remove when version 2.0.0