The JSON API specification suggests that the API returns the 403 Forbidden
error when the user does an invalid request. The 400 Bad Request isn't the
ideal error for cases where the syntax is correct but the action being
performed is wrong.
Using the JSON Pointer syntax specified in RFC 6901
(https://tools.ietf.org/html/rfc6901) allows for a convenient way to
access values deep in a JSON object.
The JSON objects that are created from the various core MaxScale objects
share a lot of common code. Moving this into a separate files removes the
redundant code.
