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 Functionally this shouldn't break in libcloud but the fixtures for the tests that are used will be a bit outdated (https://github.com/apache/libcloud/blob/trunk/libcloud/test/compute/fixtures/digitalocean_v2/list_floating_ips.json)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

Beginne mit der Überprüfung von libcloud/test/compute/fixtures/digitalocean_v2/list_floating_ips.json und create_floating_ip.json sowie der DigitalOcean-Compute-Tests, die diese verwenden. Vergleiche die Fixtures mit den angekündigten Änderungen an den Antworten der Floating IP API, führe anschließend die relevanten Tests aus und bestätige, dass die Fixtures die aktualisierten Antwortfelder abbilden.

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