Longer term, defining the policies in the application blueprint seems sensible.
And using the EntitySpec (with `PolicySpec` and `EnricherSpec`), rather than the `entityFactory`.

Moving this code into the OpenGammaClusterFactory kind-of makes sense, but also hides some of the important blueprint config.
Is the main motivation to reduce duplication between the CloudStack variant and this generic app?
The problem then is when we open this code to show someone what a blueprint looks like - we want to highlight that it's like configuration as much as is possible...