Additional bug found -ResponseId attribute

I found an additional bug while looking at the code change that would be
required to implement a switch to NCName.

The ResponseId attribute is essential to the protocol and should be
required. It was also ommitted from the examples. This has now been fixed.

I have added a switch to the code so that the examples can be generated
using either anyURI or NCName. If the examples do not match the schema the
validator throws an error.


	<element name="PendingRequest" type="xkms:PendingRequestType"/>
	<complexType name="PendingRequestType">
		<complexContent>
			<extension base="xkms:RequestAbstractType">
				<attribute name="ResponseId" type="anyURI"
use="required"/>
			</extension>
		</complexContent>
   </complexType>