improve hangout telemetry

[tansaku]

currently we only know who appeared in a hangout, but not when they arrived and left

[tansaku]

this would probably involve refactoring the data model so that rather than event instance "participants" being a text string, to the case where we had

class EventInstance
  has_many: users
end

so when the hangout sent back a participant string we would parse it into a users and link with join table.

We know at the moment at least 2/3 of users don't have G+ accounts and so won't link to existing user accounts. (we could try to calculate what percentage of participants in hangouts don't have corresponding AV accounts using G+)

QUESTION

should we have a new entity called participant to distinguish from user?

---

thinking about snapshots of the hangout

class EventInstance
  has_many :snapshots
end

snapshots initially could be just the json data and timestamp ...