title: custom sign in for devise
body: <p>Now I am using the <code>devise</code> gem, and after successful authorization it redirects user to the root page.</p>
  
  <p>How to modify <code>sign_in</code> action to return json array like this: <code>{"auth_result":"1"}</code> instead of redirect?</p>
  
  <p>Is it possible?
  I haven't found recipes for these in devise wiki.</p>