WIP: bootstrap multiple VMs on EC2

example config file:

```
vm-defaults: &vm-defaults
  provisioning_ssh_key: ../config/default.pem
  provisioning_ssh_key_name: default
  root_ebs_size: 50
  image_id: ami-d64193a1
  commen: it's ebs-ssd
  provisioning_user: ubuntu

vm-default-alias: *vm-defaults

vm-large: &vm-large
  <<: *vm-defaults
  instance_type: c3.large
  image_id: ami-3a689f4d
  security_groups:
    - default
    - ssh
    - web-server
    - salt-minion


vm-salt-master: &vm-salt-master
  <<: *vm-defaults
  instance_type: c3.large
  image_id: ami-3a689f4d
  security_groups:
    - default
    - ssh
    - web-server
    - salt-master

# zone stores credentials ('fab status' lists all vms from zone)


archipelagos:
  big:
    cm:
      driver: salt
      mastermode: True
    vms:
      repo:
        <<: *vm-large
        security_groups:
          - outbound-all
          - inbound-from-102pf
          - pkg-repo
        cm:
          grains:
            roles:
              - repo

      client:
        <<: *vm-salt-master
        security_groups:
          - inbound-from-102pf
          - pkg-repo-client
        cm:
          install: False
          grains:
            roles:
              - repo

      default: repo

  single:
    salt:
      mastermode: False
    vms:
      master: *vm-large
      default: repo

  default: big


provider_zones:
  aws_dev:
    # cloud driver
    # cloud credentials
    driver: aws
    aws_access_key_id: 'overwrite me in ~/.cotton.yaml'
    aws_secret_access_key: 'overwrite me in ~/.cotton.yaml'
    region_name: eu-west-1
```