I am using Opigno in conjunction with a main Drupal site. I have CAS setup and working, so that the user logs in on the main site and is automatically logged in to the Opigno site. The Opigno logout link, however, does not work. The user gets sent to the main Drupal site, which automatically sends them back to Opigno and they are logged in. How do I change the Opigno logout link to log out from the CAS server as well? Where is the logout link defined (it doesn't appear to be in a menu)?