Pull cold-chain temperature logger observations from Onset HOBOlink using the Web Services V3 API

Steps

1. Obtain an OAuth2 client_id/client_secret from Onset for your HOBOlink account
2. POST https://webservice.hobolink.com/ws/auth/token with grant_type=client_credentials, client_id, and client_secret to get a bearer access_token (expires in 600 seconds)
3. Call GET https://webservice.hobolink.com/ws/data/file/JSON/user/{userId}?loggers=<serials>&start_date_time=...&end_date_time=... with the bearer token
4. Parse the observation_list for logger_sn, sensor_sn, timestamp (UTC), si_value/si_unit, and sensor_measurement_type
5. For incremental pulls, use only_new_data=true with last_successful_query_time instead of a fixed date range