title: Rails - Catch 'Invalid Authenticity Token' exception
body: <p>I'm currently using RESTful Authentication plug-in on my rails application.</p>
  
  <p>There is a typical scenario when a user stays at login screen for enough time (let's say 1 day..) that makes the authentication token invalid due to time expire. </p>
  
  <p>When this user tries the next day to login (he didn't refresh, he is still with this invalid token), he will get an "500" http error. Making the application crash for that request.</p>
  
  <p>I'm wondering if it's possible to catch this expection and warn the user. Like any other innocent web user he just does back and tries again.. and again gets the same error... </p>