title: angularFire and Authentication
body: <p>Taking the TodoMVC example into consideration (<a href="https://github.com/firebase/angularFire/tree/gh-pages/examples/todomvc" rel="nofollow">https://github.com/firebase/angularFire/tree/gh-pages/examples/todomvc</a>), if I were to add authentication to this app, how could I handle the visibility of a user - i.e. if User1 adds todo items, I'd like to make sure that it's only visible to them and if User2 logs in, he doesn't see User1's items. How can I achieve this?</p>
  
  <p>On top of this - I guess this second question is somewhat relevant to the previous one - what is the best way to store todos and users and the visibility of each todo?</p>