Throw an exception when calling Auth_UserModel::getCurrentUser() if no user is logged in.

library/Unl/Controller/Helper/Authorize.php

@@ -9,4 +9,13 @@ class Unl_Controller_Helper_Authorize extends Zend_Controller_Action_Helper_Abst
 			throw new Exception('You must be logged in to view this page.');
 		}
 	}
+
+	public function isLoggedIn()
+	{
+	    $user = Auth_UserModel::findCurrentUser();
+	    if ($user instanceof Auth_UserModel) {
+	        return true;
+	    }
+	    return false;
+	}
 }