Rails with Angular and Devise

[nikhil vij]

I had a non-Angular Rails app with Devise powering the authentication. Almost all of it.

However as we are moving it to AngularJS, had a question or two about how to integrate that with Angular. 

1. What all parts of Devise can still be used? 
2. What are best practices around how to maintain session in angular? 
3. Also, how do I manage multiple roles(based on 2 different models, both devise authenticable) ?