Auth Indicators WebUI part
    
    Add custom_checkbox_widget on service page. The old  aci.attribute_widget
    now inherits from the new base class custom_checkboxes_widget and overrides
    the populate method.
    
    https://fedorahosted.org/freeipa/ticket/5872
    
    Reviewed-By: Petr Vobornik <pvoborni@redhat.com>