a43af5c webui: better value-change reporting

Authored and Committed by pvoborni 9 years ago
    webui: better value-change reporting
    
    - widget save() save method should try to always return value even if read only
    - report value-change event with actual value to allow processing of the value
    
    https://fedorahosted.org/freeipa/ticket/4402
    
    Reviewed-By: Endi Sukma Dewata <edewata@redhat.com>