Add OperationInfo extensors to generated WSDL

When generating the WSDL from a service model, the ServiceWSDLBuilder does not add extensors to operations inside a portType. While this follows the SOAP 1.1 specification, the WS-I Basic Profile 1.1 overrules this. This functionality is particularly useful for the implementation of WS-PolicyAttachment:

"WSDL 1.1 disallows the use of extensibility elements on certain elements and the use of extensibility attributes on others. However, the WS-I Basic Profile 1.1 [BP 1.1] overrules this restriction and allows element extensibility everywhere. Therefore, the Policy reference SHOULD be attached using <wsp:PolicyReference> as child element unless it is absolutely necessary to maintain the original WSDL 1.1 restriction, in which case the @wsp:PolicyURIs attribute should be used for those restricted cases."

(from the WS-PolicyAttachment W3C Submission at http://www.w3.org/Submission/WS-PolicyAttachment/#AttachingPolicyUsingWSDL1.1)

This patch adds the extensors. It builds cleanly against both 2.2.2 and the current trunk.

Please include "from University of Southampton IT Innovation Centre" in the change log.