title: How to get current user using devise in rails without using authenticate! on the controller
body: <p>I'm using devise with rails 3 and i'm trying to create a page which can be viewed by everyone (even those not signed up) but has additional functionality for people who are registered.</p>
  
  <p>The problem is that when I call current_user there is no user because I haven't used the authenticate! filter on my controller, because I want unregistered users to be able to view it.</p>
  
  <p>How do I sign in a user if they are in the session otherwise leaving it without a user?</p>