Update releases, update install process, add extra outputs for porter install

[kurktchiev]

This is a bit of a push, but it goes through and sets up our ability to use variables to control versions of components.

It also adds some sanity checks and clean-ups for the installation process.

Finally, it adds some extra outputs that are useful:

• external kubeconfig that doesn't use the internal docker network
• argocd initial password

[kurktchiev]

partially addresses https://github.com/back-stack/showcase/issues/19