meta: tests

Open questions for testing:
- We don't currently have a mock/fixture interface for a k8s cluster to test, for example, `data.ClusterIDFromPersistentStorage.Get()` against. We should consider some way to achieve a functional test of business logic which depends on a k8s abstraction.
- Same for the "Versions" API that contains authoritative deis component version data. Consider standing up a mock API so we can test code that depends on that API.

Start by reviewing data.ClusterIDFromPersistentStorage.Get() and the code that depends on the Versions API. Decide how a Kubernetes cluster fixture and a mock Versions API should be provided for functional tests. Done means business logic depending on both abstractions can be tested against controlled responses.

Written by the indexing model from the issue text.