py3: ldapupdate: fix logging str(bytes) issue
    
    bytes as argument of str() gives unexpected result by adding prefix "b"
    there.
    
    Also add missing safe_option() call to logging (it will fix another
    str(bytes) issue)
    
    https://fedorahosted.org/freeipa/ticket/4985
    
    Reviewed-By: Martin Babinsky <mbabinsk@redhat.com>