Add Linting and Formatting

[marksmall]

This PR closes #32

I have added dependencies primarily to add linting and formatting of the code-base, I then re-formatted all python code in the repo.

I also took the opportunity to add a few other helpful tools:

• Editorconfig - helps maintain consistent coding styles for multiple developers working on the same project across various editors and IDEs.
• Local virtualenv - This allows us to add vscode setting to configure linting and formatting, so each developer doesn't need to set it up themselves.
• .python-version file, so users of pyenv automatically get the right version of python set
• pytest-watch, run tests whenever a file changes
• VS Code launch configs so developers can step through code running in tests or when the app is running

NOTE: I have not tried to fix any linting issues caught. I think we should first discuss what we want from this, so it is useful first to see what it has caught. Allyn has far more experience and can guide what we should catch and what he considers less important.

[marksmall]

The tests of this PR will fail until we have merged in the changes for django-astrosat-core as it still uses drf-yasg and not drf-yasg2.