Allow to run subprocess with suplementary groups
    
    Param suplementary_groups allows to specify list of group names to be
    used for subprocess.
    suplementary_groups param requires runas param to be specified.
    
    Required for ticket: https://fedorahosted.org/freeipa/ticket/4657
    
    Reviewed-By: Petr Spacek <pspacek@redhat.com>