Add prometheus cloud storage backend for AWS

Lets start with AWS

Add a shared data volume across the slave instances so that we can place the storage for prometheus on these volumes so if the container dies and gets restarted elsewhere in the cluster we don't lose the data. How do you setup and attach a volume across multiple instances? https://www.terraform.io/docs/providers/aws/r/volume_attachment.html looks like a 1-to-1

See https://github.com/Capgemini/Apollo/pull/503