Set Allow headers as an array instead of imploding
Use the tilde operator for semantic versioning of 3rd party libs
Whitelist all Imbo headers in Access-Control-Allow-Headers
Moved the setExposedHeaders callback to the getSubscribedMethods instead. No practical difference, but I feel it fits better there as the subscribe method dynamically adds more callbacks
Check using contains so the tests does not require the implementation to add the headers in the correct order