The Auth Manager class incorporates the functionality of the
Backend.php and Auth.php class and handles authentication. The
authorization parts from the Auth.php (hasPermission(), etc.) have
been removed and will be added to the user class
refs #4265
As we decided to remove Zend_Session due to locking issues,
we have to implement our session handling here. This is
the basic, untested code which will be tested in the next step
refs #4265