DigitalOcean will change their floating IP API on the 26th of april

We just got an email from DigitalOcean stating that they will change their [Floating IP API endpoint](https://developers.digitalocean.com/documentation/v2/#floating-ips) starting the 26th. Functionally this shouldn't break in libcloud but the fixtures for the tests that are used will be a bit outdated (https://github.com/apache/libcloud/blob/trunk/libcloud/test/compute/fixtures/digitalocean_v2/list_floating_ips.json)

Changes announced by DigitalOcean:
```
The `private_networking` feature will now be listed under droplet.features instead of region.features
vpc_uuid was not being populated and will have the correct values now
The droplet.type will be "base" when the droplet is a base image (i.e. Ubuntu, CentOS).
The current value is "snapshot"
The Droplet's networking field will include any private IPs and any floating IPs which are missing from the response today
```

Test fixtures that would become 'inaccurate':
https://github.com/apache/libcloud/blob/trunk/libcloud/test/compute/fixtures/digitalocean_v2/list_floating_ips.json
https://github.com/apache/libcloud/blob/trunk/libcloud/test/compute/fixtures/digitalocean_v2/create_floating_ip.json

Comienza revisando libcloud/test/compute/fixtures/digitalocean_v2/list_floating_ips.json y create_floating_ip.json junto con las pruebas de compute de DigitalOcean que los utilizan. Compara los fixtures con los cambios anunciados en las respuestas de la Floating IP API, ejecuta después las pruebas pertinentes y confirma que los fixtures representan los campos de respuesta actualizados.

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