Make Testing Harness Permissive of Extra Data

[independentid]

The current testing harness does not permit extra attributes (e.g. context) to be provided in responses even though documented in the implementers draft.

Implementations should be able to provide extra information that also aids in debugging.

[ogazitt]

@independentid Can you please provide an example of how you invoked the harness with extra attributes? Did you change the assertions.json file in some way?

[independentid]

I didn't. That's why I raised the issue. :)