Deviation from draft4 spec - additionalItems / additionalProperties is object or boolean, not object or false.

[MrTrick]

I'm trying use the JSON-API schema inside JSCK. Schema here: http://jsonapi.org/schema

However, when I new JSCK(json_api_schema) it throws:
Error: The 'additionalProperties' attribute must be an object or false

According to the schema docs "additionalProperties": true is valid
http://json-schema.org/latest/json-schema-validation.html#anchor64

Sorry no PR yet - not so good with coffeescript.
(I will modify my local copy of JSON-API so JSCK can parse it, but this will affect other users)