From https://casablanca.codeplex.com/discussions/548792
Attempting to use ```.extract_json()``` on a request with a MIME type of ```application/x-json``` will fail with an error. While this is not the standard MIME type for JSON, it is common.
Comments: application/x-json has been added to the know json MIME types. At the same time we also added a bool parameter to extract_string and extract_json that allows extraction to be forced regardless of type.
Attempting to use ```.extract_json()``` on a request with a MIME type of ```application/x-json``` will fail with an error. While this is not the standard MIME type for JSON, it is common.
Comments: application/x-json has been added to the know json MIME types. At the same time we also added a bool parameter to extract_string and extract_json that allows extraction to be forced regardless of type.