wazo-provd-plugins: Yealink CP930W, W53H, W56H W59R plugin does not differentiate devices with same IP address

When the device tries to download a firmware, it does not send HTTP headers with information regarding which particular device it is. This results in provd not knowing which device it is and it creates a new one. It then returns 404 because it could not route the request.
I will need to investigate if it is possible to enable HTTP headers on that kind of request, or see if there is any other way to identify a device.

Technical details:

Example logs in wazo-provd.log:

Solution proposition: allow provisioning plugins to serve firmware files without needing device-specific identifiers.