Changes to WTO trade and tariff data

added the non-success response with the status 500

added the optional property meta/stale_since to the response with the 200 status

added the optional property meta/data_age_days to the response with the 200 status

added the optional property meta/notes to the response with the 200 status

added the optional property meta/period to the response with the 200 status

added the optional property data/count to the response with the 200 status

added the optional property data/data to the response with the 200 status

added the optional property data/indicator to the response with the 200 status

added the optional property data/reporter to the response with the 200 status

added the optional property data/source to the response with the 200 status

added the optional property data/year to the response with the 200 status

added the optional property code to the response with the 401 status

added the optional property code to the response with the 429 status

added the optional property code to the response with the 503 status

added the optional property hint to the response with the 401 status

added the optional property hint to the response with the 429 status

added the optional property hint to the response with the 503 status

added the optional property plan to the response with the 401 status

added the optional property plan to the response with the 429 status

added the optional property plan to the response with the 503 status

added the optional property reason to the response with the 401 status

added the optional property reason to the response with the 429 status

added the optional property reason to the response with the 503 status