Fix Dockerfile
Fix Dockerfile

Hey, this works now!
I switched the default shell ('/bin/sh') and also added the common commands I
entirely forgot.
Docker runs each command in order, except for some specific like 'CMD'.
Here is a brief explanation of used commands:
  - RUN: Run commands using a shell
  - SHELL: defines the basic shell to be used for 'RUN'
  - COPY: Copies files from the filesystem to the docker image.
  - CMD: Defines the command to run when invoking 'docker run' on this image.

I will soon change the Dockerfile to a much more compact and common version.

dan-gittik/example,dan-gittik/example