Add metadata on AWS box creation
Set hostname when creating servers
Put the hostname in /etc/hosts

Salt will manage this file later, but make `hostname -f` and `sudo` not
complain until then
Force minion id to be a string, not a unicode string
Abstract AWS tagging of env/project to api.py
Merge pull request #41 from ministryofjustice/add_metadata

Add metadata and set hostname of generated VMs on AWS.