New interface to save configuration in a file
    
    The patch adds declaration of the new interface
    that allows saving configuration in a file,
    creating backups and changing file permissions
    and ownership.
    
    Signed-off-by: Dmitri Pal <dpal@redhat.com>
    Signed-off-by: Lukas Slebodnik <lslebodn@redhat.com>
    
    Reviewed-by: Lukáš Slebodník <lslebodn@redhat.com>