Review items for 'Make branch attribute available when publishing and resolving Ivy modules' story

- Changed groovy.xml.QName to javax.xml.namespace.QName
- Minor change to error message and construction of namespace list
- Minor change to dsl doc
- Changed IvyModuleDescriptorSpec to return mutable view of IvyExtraInfoSpec
- Minor change to sample build script
+review REVIEW-5059