Query parameter content-type json serialization was broken, so I fixed it
This PR

• fixes that feature
• adds a test of query param content type json serialization in test_query_content_json_serialization
• adds an endpoint to the sample spec that uses it at /fake/queryParamWithJsonContentType
• adds a verification endpoint method call for that endpoint at TestFakeQueryParamWithJsonContentType.test_get

This issue made me realize that the query parameter json serialization is broken and needs:

• whitespace removal between items and key value pairs
• percent encoding of values

When working on this issue, I filed this issue for the future:
#34

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