API - Device status added

✨ Improvements

Properties active and started have been added to the segment object to the /devices and /locations endpoints. The active field is used to distinguish between devices that are currently paired to an account and devices that have been unpaired and removed from the account, but still have historical measurements.

The segment object now has the following structure:

{
  "id": "91f7fc45-8006-4279-9b0a-fa8b812020fa",
  "name": "My device name",
  "started": "2020-08-07T06:53:04",
  "active": true
}