Pack DrWatson project into a container

Two things that occurred to me while working with DrWatson:

1. How do you deal with unregistered packages that are not exclusively part of the DrWatson project?
2. It would be cool to have a functionality to "pack" an entire DrWatson folder into a docker image.

ad 1.: I thought of setting up my own registry but currently maintaining versions is tedious. Another solution that seems plausible is dev_ing the package with a relative path outside of the DrWatson project and assuring that the other person has the same folder structure. However, also not really portable. What I did in order to be able to easily send the project over to a colleague is adding the package to a subfolder (like dev) using git subtree. Can you think of a better solution? If we find one we could add this to the docs.

ad 2.: We could add a function that generates the dockerfile. Like:

1. get julia image version from project.toml
2. On build move entire project into the container
3. Also on build instantiate and precompile
4. Start container
5. Build and tag the image

This could also be useful for archiving projects. I always worry about needing a project again after some time (year) and finding that nothing works anymore ... But maybe thats a pre .7 fear ;)