Kube auth

[GKTheOne]

Pull Request Checklist

This is for #9, and hopefully resolves the build errors.

General

• [x] Update Changelog following the conventions laid out on Keep A Changelog
• [x] Update README with any necessary configuration snippets
• [?] Binstubs are created if needed
• [x] RuboCop passes
• [x] Existing tests pass

  Purpose

Initially used Danni's code, then refactored and added ssl client cert options along with an easy-to-use incluster flag.

[GKTheOne]

I should mention that my only ruby (and open source project contribution) experience is this work. So please be gentle. 😃 And some feedback on what I've done right, wrong, or just bizarrely would be welcome please.

[sstarcher]

@GKTheOne looks like some good changes. I should be able to look over it and test it out this weekend.