Pull request for attaching the UTC timestamp and timezoneOffset to objects from the old parsers

This pull request generates a `ts` field on events, which is the timestamp in Zulu-time, UTC.  It also generates `timezoneOffset` as specified in the new data model spec.

I did not use `time` because the current blip code uses the presence of the `time` field as an indicator that the data is in the "new" format.

Once these parsers get re-written to generate that format, they should emit the time field.  Until then, they can emit ts and deviceTime and we can go from there.

@kentquirk @jh-bate LMK what you think.
similar question to @kentquirk - should this and the function deviceTimeToUtc belong in sundial?