Add missing key for users plugin

Author: ravage84

config/users.php

@@ -14,6 +14,8 @@
 
 $config = [
     'Users' => [
+		// Controller used to manage users plugin features & actions
+		'controller' => 'CakeDC/Users.Users',
         'Registration' => [
             //determines if the register is enabled
             'active' => false,