Changes to Compare latest vs a named vintage for one series

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/country to the response with the 200 status

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

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

added the optional property data/vintage_dataflow 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

endpoint added