Dockerfile quicky - templating with M4

Creating abstracted Dockerfile is something I really wish existed. Every time, I write a `Dockerfile` for a specific base image I must specify the correct package manager command. You either use `apt-get` or `apk` or `yum` or any other call for the package manager. This is unfortunately, not very reusable. But, here is a simple schema how to use M4 macros to achieve this abstraction.