title: Commander not using default values
body: <p>I setup commander with defaultArgs like this:</p>
  
  <pre><code>import * as validations from './validation'
  import program from 'commander'
  import path from 'path'
  
  export default function initializeCommander (defaults) {
    program
      .version('0.0.1')
      .usage('redbubble-demo')
      .option('-u', '--url [url]', validations.isValidUrl, defaults.url)
      .option('-o', '--output-dir [path]', validations.hasValidParentDirectory, path.resolve(defaults.path))
      .option('-s', '--size [size]', validations.isValidSize, defaults.size)
      .parse(process.argv)
  
    return program
  }
  </code></pre>
  
  <p>I have the default values set up here and pass them to the function like this:</p>
  
  <pre><code>const defaultValues = {
    url: 'someuRL',
    size: 'medium',
    outputDir: './www'
  }
  const program = initializeCommander(defaultValues)
  console.log(program) //no value in console
  </code></pre>
  
  <p>When I try and access the options from <code>program</code>, i get no values.</p>
  
  <p>I call my app without any arguments using:</p>
  
  <pre><code>babel-node src/index.js
  </code></pre>
  
  <h1>UPDATE:</h1>
  
  <p>I am able to run the app as a binary now using <code>npm link</code> but i get this error:</p>
  
  <pre><code>TypeError: Path must be a string. Received undefined
      at assertPath (path.js:7:11)
      at Object.resolve (path.js:1146:7)
      at initializeCommander (/home/vamsi/Do/redbubble-demo/build/index.js:9889:222)
      at Object.&lt;anonymous&gt; (/home/vamsi/Do/redbubble-demo/build/index.js:87:34)
      at __webpack_require__ (/home/vamsi/Do/redbubble-demo/build/index.js:22:30)
      at /home/vamsi/Do/redbubble-demo/build/index.js:42:18
      at Object.&lt;anonymous&gt; (/home/vamsi/Do/redbubble-demo/build/index.js:45:10)
      at Module._compile (module.js:541:32)
      at Object.Module._extensions..js (module.js:550:10)
      at Module.load (module.js:458:32)
  </code></pre>
  
  <p>The line numbers in the <code>stack trace</code> are off because I am using <code>webpack</code> to bundle it.</p>