Add support for multiple clusters / versions

[PhilippeAB]

Need the port to be configurable

[myii]

@PhilippeAB Port is now configurable.

[myii]

@noelmcloughlin I don't think this issue should be closed just yet. Allowing the port to be configurable was just the first stage. As I've said in #218 (comment), this progress can now be built upon to support multiple clusters/versions.

[noelmcloughlin]

True. I closed because the issue description only requested a configurable port. I now see slogan is talking about multiple cluster / version. Thats fine.