Various housekeeping tasks

[dougiesquire]

This PR includes a range of housekeeping tasks:

• add LICENSE
• add setup.py
• add CONTRIBUTING.md
• expand .gitignore
• add versioneer for automatic versioning from git info
• add pre-commit hooks running black and flake8
• add github Action running:
  • a tests workflow (pytest including codecov on various platforms and Python versions)
  • a pre-commit workflow
• add some badges (currently not working as they point at the AusClimateService repo which doesn't have Actions until this PR is merged)

Closes #7

[dougiesquire]

You'll see the pre-commit Action is currently failing. There are a few errors that I have instructed flake8 to ignore in order to get this moving forward (see .pre-commit-config.yaml). However, I didn't want to ignore F821. Ideally we would fix up all the errors flagged by flake8 and then ignore nothing in .pre-commit-config.yaml.

[dougiesquire]

Note I made this branch off of #5, so it's probably best to get that merged first and then merge this.

[DamienIrving]

Thanks, @dougiesquire!

I'll fix up the conflicts and then merge