Added a method to RNFCacheHandler protocol to know if an operation should be cached or not.
Added a simple dictionary-backed user defined parameters handler, and this is used into RNFDictionaryEndpointConfiguration as well, tests passing
responseValidator and responseDeserializer don’t return Class values anymore, tests updated and passing
Closes #41, more checks are now enforced for Dictionary-based configurations. Tests should be written for dataSerializer and dataDeserializer for all the dictionary-based configurations (endpoint and operation), plus the unified configuration. Tests should also be created for a simple dictionary-based response validator