Timestamp in Agency

[hunterowens]

Per @HenriJ

`Could we add a timestamp field the event so that if we receive it later, we can know the real time when it occurred ?

[hunterowens]

@CityOfLosAngeles/ellis-associates can you document how to pass time in the past in a request to an Agency API server? The use case @HenriJ and I are trying to document is a recursive trip_start call, but that may be gone now that we are hard bounding trip_start and trip_leave.

[toddapetersen]

Latest version of Agency includes a timestamp associated with every event and telemetry point.