title: aws ecs-cli extra-user-data: flag provided but not defined
body: <p>I'm facing a strange problem trying to configure a AWS ECS cluster through ecs-cli.
  To be specific, if I use the flag --extra-user-data it says: flag provided but not defined.</p>
  
  <p>here's my command syntax: </p>
  
  <pre><code>ecs-cli up --capability-iam --keypair test --size 1 --instance-type t2.small --extra-user-data file://init-ec2 --launch-type EC2 --force --cluster test --region eu-west-1
  </code></pre>
  
  <p>Here's the exception: </p>
  
  <blockquote>
    <p>ERRO[0000] flag provided but not defined: -extra-user-data</p>
  </blockquote>
  
  <p>Any help is appreciated...</p>