Monkeypatch libcloud to give it support for the eu-central-1 ec2 region.

[ralphbean]

This monkeypatches libcloud at runtime to give it support for the ec2 eu-central-1 region which it amazingly doesn't have support for out of the box. We have to define a driver for it and then inject our driver into its registry of providers.

We call it from two places, where fedimg could possibly be starting up.

• From the consumer, for when fedimg is running in the background under the fedmsg-hub.
• From the trigger-upload script, for when fedimg is running manually in the foreground.

[pypingou]

Let's keep #40 instead