Docker build features

Determine whether the docker build should be an entity, or if managing a file directory is sufficient.

Dockerbuild features:

- Docker builds will be physical files in the private file system.
- The machine_name will be the directory name.
- The actual Dockerfile should be editable via a textarea.
- Docker builds can be imported as a compressed file (formats?)
- Docker builds can be exported as a compressed file
- Docker build file system needs to be browsable, or at least the file tree needs to display somewhere
- An image should be able to be built on any Docker host (requires compression & file stream)