title: babel v6 + react-intl v2 + webpack extraction of messages to file
body: <p>I would like to extract the messages from the source code to a JSON file, using Babel v6, react-intl v2, and webpack. It's all compiling fine, but not extracting anything. How do I make v2 of react-intl properly extract the messages?</p>
  
  <p>There's an option <code>messagesDir</code>:</p>
  
  <h2>I've tried:</h2>
  
  <ul>
  <li>new file <code>.babel.rc</code> from here: <a href="https://github.com/yahoo/babel-plugin-react-intl/issues/23" rel="nofollow noreferrer">https://github.com/yahoo/babel-plugin-react-intl/issues/23</a> – probably misspelt name, should be <code>.babelrc</code>.</li>
  <li>new file <code>.babelrc</code>:</li>
  </ul>
  
  <pre><code>{
    "extra": {
      "react-intl": {
        "messagesDir": "./i18n",
        "enforceDescriptions": true
      }
    }
  }
  </code></pre>
  
  <p>With webpack config</p>
  
  <pre><code>{ test: /\.js$/,
    loader: 'babel-loader',
    query: {
      // react needed for JSX syntax
      // es2015 needed for modules
      // stage0 needed to do splats (...variable)
      presets: ['react', 'es2015', 'stage-0'],
      // react-intl extracts i18n messages to a shared file
      // add-module-exports removes the need to do `require('a').default`
      plugins: ['react-intl', 'add-module-exports'],
      cacheDirectory: true
    },
    exclude: /node_modules|bower_components/
  },
  </code></pre>
  
  <p>gives: "index.js: Unknown option: /.babelrc.extra" as the error message.</p>
  
  <p>I've tried adding the above <code>extra</code> property to the webpack configuration above, too. It gives a very similar error message.</p>
  
  <p>Versions:</p>
  
  <pre><code>✗ npm ls | grep "intl"
  ├─┬ babel-plugin-react-intl@2.0.0
  │ └── intl-messageformat-parser@1.2.0
  ├── intl@1.0.1
  ├── intl-locales-supported@1.0.0
  ├── intl-messageformat@1.2.0
  ├─┬ react-intl@2.0.0-pr-3
  │ ├── intl-format-cache@2.0.4
  </code></pre>