variable refactor
- simplify packer template, remove nodes dir, only keep aws-template.json -> aws.json
- add gui, branch as facter variables
- name (hostname, client id) and node (manifest) different, name falls back to node
- add variables for facter facts in packer template and Vagrantfile
- prefix aws box-name with 'aws'
- AWS_REGION comes from aws.env
- rewrite README accordingly