household_people joins a roster family to the accounts of its parents; a
household can have two, a person can rarely be on two. PUT
/roster/households/{id}/people sets it (admin and above). GET /family
(account:self) returns the signed-in person's own households with scouts
and this year's checklist, and nothing else - the parent view of the
roster, read only. Inactive households drop off it.
tests/smoke_admin.py 141 -> 147.