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 Functionally this shouldn't break in libcloud but the fixtures for the tests that are used will be a bit outdated (https://github.com/apache/libcloud/blob/trunk/libcloud/test/compute/fixtures/digitalocean_v2/list_floating_ips.json)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

Inizia esaminando libcloud/test/compute/fixtures/digitalocean_v2/list_floating_ips.json e create_floating_ip.json insieme ai test di compute di DigitalOcean che li utilizzano. Confronta i fixture con le modifiche annunciate alle risposte della Floating IP API, quindi esegui i test pertinenti e conferma che i fixture rappresentino i campi di risposta aggiornati.

Scritto dal modello di indicizzazione a partire dal testo della issue.