title: Client error (AuthFailure) occurred when calling the DescribeInstances operation
body: <p>I am getting the following error when trying to run flightplan to push to staging.</p>
  
  <p>I have a colleague who is using this exact git repo and the same credentials and his works, but mine is throwing this error. Any idea why mine isn't working? Is there something I need to install?</p>
  
  <pre><code>Benjamins-MBP:XXXXXXX-deploy Ben$ fly --flightplan web-flightplan.js staging --keyfile=/Users/Ben/.ssh/XXXXXX-web-key-pair.pem
  Fetching instances for group: 'XXXXXXX-staging-web'
  
  A client error (AuthFailure) occurred when calling the DescribeInstances operation: Authorization header or parameters are not formatted correctly.
  ● Error: Command failed: /Users/Ben/git/XXXXXX-deploy/app/../scripts/get_aws_instances XXXXXXX-staging-web
  
  A client error (AuthFailure) occurred when calling the DescribeInstances operation: Authorization header or parameters are not formatted correctly.
  
      at checkExecSyncError (child_process.js:441:13)
      at execSync (child_process.js:481:13)
      at Object.module.exports.fetch (/Users/Ben/git/XXXXXXX-deploy/app/instance-fetcher.js:11:27)
      at Object.&lt;anonymous&gt; (/Users/Ben/git/XXXXXXX-deploy/web-flightplan.js:40:31)
      at Module._compile (module.js:435:26)
      at Object.Module._extensions..js (module.js:442:10)
      at Module.load (module.js:356:32)
      at Function.Module._load (module.js:311:12)
      at Module.require (module.js:366:17)
      at require (module.js:385:17)
  </code></pre>
  
  <p>Client code for describeinstances op:</p>
  
  <pre><code>#!/bin/bash
  
  GROUP=$1
  if [ -z "$GROUP" ]; then
      echo "Specify group as only parameter"
      exit 1
  fi
  
  DIR="$( cd "$( dirname "${BASH_SOURCE[0]}" )" &amp;&amp; pwd )"
  
  . $DIR/aws_keys
  . $DIR/aws_region_us
  
  aws ec2 describe-instances --filters "Name=tag:group,Values=$GROUP"
  </code></pre>