report daily instance activity
This merge request adds the new daily instance usage API, deletes the old prototype "hourly usage" report API, deletes some old infrastructure that only served the old prototype, and retrofits most of the old prototype's tests to apply to this new API.
Some of the changes appear pretty big, and since there's a lot of deleting and editing going on, you might want to review this in the side-by-side view instead of inline. Also, don't forget to expand some of the auto-collapsed diffs for the longer files.
Demo, part 1: https://asciinema.org/a/192092 Demo, part 2: https://asciinema.org/a/192237
Edited by Brad Smith