Refactor image builds

[mnaser]

This change introduces multi-stage image builds where it uses the upstream Golang image to build the project and then places it in an empty, scratch container to run it inside.

This increases the security of the container significantly due to the fact that you don't have an operating system alongside it that you need to keep up to date. It also drives the size of the image down.

This does introduce a small behaviour change in that you must manually setup your arguments and you no longer automatically have the configuration file auto-detected, but it's probably better for users to explicitly configure things rather than have it implicitly happen.