[Devices] Ability to list devices associated to a given user

[josephpage]

As already discussed with Xee team, this route is a must-have.
Hope you will be able to release it in few days/weeks.

GET /v3/users/{userId}/devices

[
  {
    "deviceId": "E160000000",
    "carId": 10000   # associated to a car
  },
  {
    "deviceId": "E160000000",
    "carId": null    # no car associated yet
  }
]

If possible to implement (in future releases), the following fields could be usefull :

• timestamp of first data from this device
• timestamp of last data from this device
• cardbId detected