Device Registry: deprovision a device

[bennage]

Please see #201 for context.

We want an API that allows us to provision a device for authentication with the backend.

• POST a GUID respresenting the device identifier
• return the appropriate response code if the device is already deprovisioned
• using the Service Bus APIs described in #156 invalidate the credentials associated with the device id
• update the associated record in the registry with device status deprovisioned