Python runner POC

[turekj]

Hey @orta!

I have tried to build upon the initial implementation to create a project similar to the Danger Swift. Currently, the runner:

• delegates ci, local and pr commands to danger-js passing itself as a runner,
• implements default run command that executes contents of dangerfile.py and reports the result back to danger-js process,
• provides the rudimentary implementation of Danger DSL parsing (only a handful of properties of the JSON are read),
• provides methods for writing to output (warn, fail, message, markdown).

Please, let me know what is your general feedback on this and what would it take to merge the PR into the master of the repository.

To test the app, you can emulate the steps provided in the README:

# install danger
npm install -g danger
# install poetry
pip install poetry
# install project dependencies
poetry install
# activate virtual environment
poetry shell
# run danger-python
danger-python pr https://github.com/microsoft/TypeScript/pull/34806

I've only tested the setup with Python 3.7 running on MacOS 10.15.2.

[orta]

If you're happy, I'll merge and you'll get an invite to be a member of the org. WRT this repo, I trust you to know more about the python ecosystem and the way in which Python danger should feel. I will assist however I can.

I'll be around to help answer questions, and provide someone for a reasonable code review and you have a slack invite so that you can directly ping me synchronously if needed.

[turekj]

I've updated the authors and I think we're ready to merge this part 👍 I'm happy to continue the work on the DSL and the plugins later. Thank you for the review! 🙇

[orta]

👍