title: mantis time out issue
body: <p>I have configured Mantis, the thing is after sometime if I stay idle, Mantis sort of timeout. I refresh the page again and again but it does not load Mantis at all. Whenever I restart XAMPP it starts working fine (until I don't sit idle).</p>
  
  <p>Here are some settings that i have seen w.r.t exipration </p>
  
  <pre><code># token expirations
  define( 'TOKEN_EXPIRY', 60 * 60 );
  
  # Default expiration of 60 minutes ( 3600 seconds )
  define( 'TOKEN_EXPIRY_LAST_VISITED', 24 * 60 * 60 );
  define( 'TOKEN_EXPIRY_AUTHENTICATED', 5 * 60 );
  define( 'TOKEN_EXPIRY_COLLAPSE', 365 * 24 * 60 * 60 );
  </code></pre>
  
  <p>Can someone tell me how to get through this timeout thing whatever it is? I am using "Mantis 1.2.8".</p>