new ServiceContractResolver that cxf can resolve wsdl file from extension repository/storage

currently, cxf support get wsdl URL from local file or internet location. we can add ServiceContractResolver interface make cxf can get wsdl file from extension repository/storage like zip files, UDDI repository, DB storage, etc..

interface ServiceContractResolver

{ URL getContractURL(QName); }

and bus extension to register and unregister resolvers into cxf bus:
interface ServiceContractResolverRegistry

{ //cxf bus extension URL getContractURL(QName); void register(ServiceContractResolver); void unregister(ServiceContractResolver); bool isRegistered(ServiceContractResolver); }

;