Authenticate user using CAS.
You have to set it up correctly in conf/bootstrap_plugins.php using the following keys in $PLUGINS["AUTH_DRIVER"]["OPTIONS"] array:
CAS_SERVER: hostname of the CAS server (example: login.example.com) CAS_URI: URI where CAS server is installed on (example: /cas) CAS_PORT: port where CAS server is listening on waiting for connections USERS_FILEPATH: Inherited from auth.serial. File where user data is stored