Update spec.json

Python class field was added into method spec.
Some error cases were added into test branch of method spec repo.
Merge branch 'test' of https://github.com/msneddon/narrative_method_specs/ into test
Error test was corrected.
Method spec for testing parameters mapping to service method arguments.
Update spec.json

Fix of JSON format in parameters mapping test case.
Update display.yaml

Testing refresh mechanism