Please upgrade to newer version of Docker

[siddhuwarrier]

The AMIs used currently use Docker v1.4.1. Docker hub no longer supports a Docker client that old. So it fails to pull from the registry.

I have an alternative AMI in the eu region that uses a newer version. If you might be amenable to using that, I'd be happy to send you a PR with the updated AMI ID for eu-west-1 (I'd need to get permission from my boss to make the AMI public first, but I thought I'd check with you beforehand).