Enviro+ Case Top

Using the base case from barnestom, I have added a top case to fix the Pi zero and the enviro+ hat because I do not have a right angle header.

To make even better, I should rework the barnestom case to have a hole to get access to the power supply connector of the Pi Zero. For the time being and because I do not have the files from barnestom, I just cut a hole afterwards.