adds aws role support to init (closes #174)

[jritsema]

harbor-compose init
...
would like you to use an AWS IAM Role? (y|n) y
which SAML user would you like to grant role access to? (e.g., aws-digital-sandbox-devops/First.Last@turner.com) 

# add aws resources to main.tf
terraform apply

• add newly created role to docker-compose.yml

  role:
  image: quay.io/turner/ectou-metadata
  ports:
  - 9000:80
  environment:
  
    # the role you want your container to assume
    ROLE: arn:aws:iam::123456789:role/my-role
  
    # the local profile you want to use to assume the role
    AWS_PROFILE: ${AWS_PROFILE}

• docker-compose up to test locally in docker
• harbor-compose deploy