feat: use scaleway-sdk-go instead go-scaleway

[yocarbo]

Hi,

A quick and dirty but functional code with scaleway-sdk-go instead go-scaleway.

Create, start, stop, remove machine with Gitlab runners :

  [runners.machine]
    MachineDriver = "scaleway-v2"
    MachineName = "runner-%s"
    IdleCount = 0
    IdleTime = 180
    MachineOptions = [
      "scaleway-accesskey=********",
      "scaleway-secretkey=********",
      "scaleway-project-id=********",
      "scaleway-name=runner-1",
      "scaleway-commercial-type=DEV1-M",
      "scaleway-zone=fr-par-2",
      "scaleway-image=docker"
    ]

The "big" problem is to sync the ssh key from docker-machine to scaleway instance (read the cloudInit() method into the code).
Some old options are not implemented like scaleway-volume, scaleway-user/port.

I hope I have helped a little bit to use the Scaleway driver with Gitlab. (#99)

Pending official v2 and use MachineDriver = "scaleway-v2" :
go build -o docker-machine-driver-scaleway-v2

Regards,