Phase 1: Withings service updates

- Working around Withings API (limits and filtering).
- Cannot use withings gem user#meausrement_groups for retrieving user measurements since it does not handle batching.
- Updating code that relies on the import.
- Do not try to re-authorize with withings if there is a valid authorization access stored.
maybe assign `user.scale_measurements.first` to a variable for ease of change and readability