Update tests to show how you'd test against a live API

[FokkeZB]

The tests in the sample app use an endpoint that is hard-wired to accept code:one_time_code, access_token:a_token and refresh_token:a_refresh_token. This will fail for any other, live API.

The tests should show how to test an OAuthV2 API and deal with the (expiring) access tokens. Should you get your hands on a token and update that every time you run the tests (like we do for Python apps)? Is there another way?

Perhaps a link to https://github.com/zapier/zapier-platform-example-app-onedrive#testing will do?