Caching not working with RedisStore Cache

Using Rails.cache as a resource_cache appears to make the caching fail when config.cache_store is redis_store.

I think the reason is due to the way Redis Cache serialise key as string when they are arrays.

When the key(an array) is serialised in the self.write method of CachedResourceFragment
https://github.com/cerebris/jsonapi-resources/blob/master/lib/jsonapi/cached_resource_fragment.rb#L122 it is serialised as a string.
When the value is retrieved in the lookup method the hash hits returned by the read_multi methods has keys that are not array, but strings. The method has_key? is then failing returning false instead of true.
https://github.com/cerebris/jsonapi-resources/blob/master/lib/jsonapi/cached_resource_fragment.rb#L81

Simple example, with config.cache_store = :redis_store

Rails.cache.write([1,2], 'value')
hash = Rails.cache.read_multi([1,2])
# returns false
hash.has_key?([1,2])

I've tried to serialise manually the keys (https://github.com/cerebris/jsonapi-resources/compare/master...x4d3:master) without success, the test are failing.

Thank you,

Start in lib/jsonapi/cached_resource_fragment.rb at lookup and self.write, then reproduce the Rails.cache.read_multi example with config.cache_store set to :redis_store. Compare the key types returned by RedisStore with the array keys used by has_key?; done means cache hits are recognized and the existing tests pass.