Watching CRDs is not supported

#65 added support for decoding & encoding custom resources - when a Kazan.Request is built with a custom resource as it's response_model we'll succesfully decode that custom resource.

Watch request decoding however uses the kind field in the object in the WatchEvent. The lookup table for kinds is generated at compile time, so custom resources will not be included in this. We probably need to update the lookup table to be dynamic somehow.