Continuous Integration/continuous deployment demo

We'll use Travis CI to run our tests and deploy to Heroku if the tests pass each time we push to master.

Checklist

• Ensure Travis CI has access to the user account/org
• Switch on the repository on the profile
• Add a .travis.yml file
• Install the Travis CI and the Heroku CLI tools
• Add the required settings in the .travis.yml file
• Push to GitHub