Make it easier to run Tier2 outside of a kubernetes cluster

[jaharkes]

Right now we need to have kubectl/helm access to the cluster, but also expose the prometheus endpoint with a combination of kubectl port-forward and overriding the prometheus endpoint url (--prometheus) to point at the forwarded port.

Having some startup tests to see if kubectl/helm and the prometheus endpoint are accessible and then either failing or automatically setting up the required port forward would make it a lot easier for developers who are working on Tier2 from their development environment.