Add Python API and REST and web interfaces #43
Description
Currently the xcetool CLI entry point is effectively the only "proper" API for xcengine. Of course the Python package can be imported and used, but the API isn't formalized and some functionality is only available in the CLI functions. For deployment in the cloud and integration into scientific workflows, we should have the following:
- A formalized Python API acting as a common backend
- The existing CLI as a thin-as-possible wrapper around the API
- a REST API
- a web API -- can be as simple as a single form accepting notebook and environment.yml as uploads or URL.