<ProvideTransfer> will not provide transfer if there is no peer

The <Peer> element is optional, but if it is removed then not transfer can be done. This behavior contradict the name of the <ProvideTransfer>. Maybe we should:

• Make the <Peer> element oneOrMore rather than zeroOrMore.
• Or make zone transfers open if there is no peer defined.

                <Outbound>
                        <ProvideTransfer>
                                <Peer>
                                        <Prefix>0.0.0.0/0</Prefix>
                                </Peer>
                        </ProvideTransfer>