Removing Travis and replacing with GitHub Workflows

[glynnbird]

Overview

ASF has requested that Travis not be used. This PR attempts to replace the running of automated tests with GitHub workflows.

In the Travis implementation we used a couple of shell scripts to spin up CouchDB in Docker for testing over localhost. These scripts have been removed (together with the travis yml) as the GitHub Actions implementation uses a CouchDB "service" in GHA.

This implementation complies with the ASF's GitHub Actions Policy by only using GitHub's own actions: see https://infra.apache.org/github-actions-policy.html

Testing recommendations

See if automated tests run successfully.

Checklist

• [x] Code is written and works correctly;
• [x] Changes are covered by tests;
• [x] Documentation reflects the changes;