Setup continuous integration tools

[kfrz]

Background

We should have some CI/CD tooling in place to run automated tests/linters etc. as well as for ease of deployment.

All the following options have free tiers for open source:

CircleCI
Travis
Semaphore

We could also just use builtin Heroku CI if that's where we're launching

Definition of done

• A successful test deployment
• A successful CI run
• Create documentation for the group capturing the details of the deployment process