* feat: add model to track session attendance
* feat: add model to track session attendance
* feat: add api to set session attendees
* fix: use user pk instead off person pk in the attended api.
* feat: calculate three of five from attended
* feat: management utility to populate Attended model history
* docs: document why nomcom calculations don't use Attended yet.
* fix: add migration to add new personalapikey endpoint to choices
* test: verify very old last login prevents api key use,
* chore: address review nits
* chore: comment on some idiosyncracies of the expected input to populate_attended
* fix: add unique_together constraint for the Attended model
* fix: correctly handle empty querysets passed to three_of_five_eligible functions.
