Resolve "Add docker file and image"

Closes #6 (closed)

This merge request

• Adds a Dockerfile to create a minimal image to be able to run quick CI and (in the future) to build and deploy micadowise through conda (see !5 (merged)). The image is uploaded to the registry.
• Adds a simple .gitlab-ci.yml to run quick CI for feature branches.
• Moves the micado-wise source to src/micado, a necessity to make the CI work because the repository name (micadowise) is not the same as the Python package (micado).