Add CI for unit tests / coverage testing

[mlandauer]

• [X] Run unit tests (except those which require a yinyo server) in a CI system
  • Implemented using Github Actions in #114
• [x] Add coverage tests (implemented in #127)
• [x] Add some notifications for tests passing/failing

[jamezpolley]

I've written up a proposal which may make this easier in #99. I've partially implemented the proposal from #99 in #100.

Edit: Nope, I don't think #99 makes this any easier.

[mlandauer]

@jamezpolley what's the state of this now? I'm figuring the CI bit is done, with github actions? Do we get notifications if the build fails? Also, is there coverage testing?

[jamezpolley]

127 expands the CI to add a lint check; coverage testing with coveralls; and a badge to show the current CI status as well.

I'm leaving that for you to merge as the lint check is currently failing. I don't know if you'd prefer to merge that and then fix the lint errors, or if you want to fix the lint errors in the branch before it merges.

[jamezpolley]

Notifications are already going to slack (eg, https://oaf.slack.com/archives/C2XD5LDN1/p1577158705005500) and I'm getting emails (I've shared one with you in Front)

[jamezpolley]

@mlandauer Assigning back to you as I'm waiting for your feedback in #127

[jamezpolley]

This seems to be complete.