Consider adding a Dockerfile for development?

[jechols]

In order to help debug some of the shell execution processor's issues, I found myself not having much luck with local dependencies, so I set up a dev-specific Dockerfile and even docker-compose.yml. It's a bit rough around the edges, but it might make contributions and local testing a bit easier.

I don't want to submit a PR on this unless there are definitely others with the same need, and don't mind how hacky this is, so here's a branch on my local fork: https://github.com/jechols/hydra-derivatives/tree/feature/docker-as-a-vm. Enjoy or ignore at your leisure.