Create events endpoint

[KristinaRiemer]

Need to identify goal(s) for day-long hackathon on 1/26

• before meeting, get BrAPI up and running (ask Chris for help)
• Start adding one of the new endpoints (events?) https://github.com/terraref/brapi/issues?q=is%3Aissue+is%3Aopen+label%3Aardn
• publish stuff already on NAL

All ARDN notes

[KristinaRiemer]

David, Chris, and I spent the entire hackathon time working on this new BrAPI endpoint, with a successful first version by the end. It required creating a new events.py file, updating the brapi.yaml and calls.py. Most is in this commit by @dlebauer, with followup improvements in issue 49.