Fix for "The page at https://*.sharepoint.com/* ran insecure content from http://{3rdparty_json_api_call}" error in a NAPA app

If you are receiving data through a JSONP API call from a third party service in your SharePoint 2013 NAPA app and you get an error of this pattern -
"The page at https://*.sharepoint.com/* ran insecure content from http://{3rdparty_json_api_call}"

... make the JSONP API call from its equivalent HTTPS URL i.e. replace http with https. This fix will work provided the third party API supports HTTPS.