- Change cluster factory to use default_environment
- Add a constant on cluster to declare default environment
- Change find_cluster_platform_kubernetes to search for a specific
  environment on EE, and ignore environment argument on CE
- Override find_cluster_platform_kubernetes and deployment_platform
  methods
- Remove memoization frmo deployment_platform on EE, otherwise when
  searching for a another platform, once the first one is assigned,
environment parameter is completely ignored