Properties for hiding secret data of configuration

It is possible to hide some of the parameters in the configuration.
For example:
```php
'panels' => array(
    'YiiDebugToolbarPanelSettings' => array(
        'hiddenList' => array(
            'components.db.username',
            'components.db.password',
        ),
        'hiddenValue' => '*****',
    ),
),
```