title: fetch method is not defined using ES6 fetch in React
body: <p>I have a trouble with fetch functions in my first react js app.</p>
  
  <p>This is the structure of my project:</p>
  
  <pre><code>hello-world
    -- app
       -- components
         -- main.jsx
    -- node_modules
    -- public
       -- build.js
       -- index.html
    -- package.json
  </code></pre>
  
  <p>This is what I've installed using npm:</p>
  
  <pre><code>npm install react react-dom babel-core babel-loader babel-preset-es2015    babel-preset-react webpack --save-dev
  npm install --save isomorphic-fetch es6-promise
  </code></pre>
  
  <p>I use webpack
  webpack.config</p>
  
  <pre><code>module.exports = {
    entry: './app/components/main.jsx',
    output: {
      path: './public/',
      filename: "build.js",
    },
    module: {
      loaders: [
        {
          exclude: /(node_modules|bower_components)/,
          loader: 'babel',
          query: {
            presets: ['es2015', 'react']
          }
        }
      ]
    }
  };
  </code></pre>
  
  <p>package.json</p>
  
  <pre><code>{
    "name": "hello-world",
    "version": "1.0.0",
    "description": "",
    "main": "webpack.config.js",
    "scripts": {
      "build": "webpack -w"
    },
    "author": "mannuk",
    "license": "MIT",
    "devDependencies": {
      "babel-core": "^6.14.0",
      "babel-loader": "^6.2.5",
      "babel-preset-es2015": "^6.14.0",
      "babel-preset-react": "^6.11.1",
      "react": "^0.14.8",
      "react-dom": "^0.14.8",
      "webpack": "^1.13.2"
    },
    "dependencies": {
      "es6-promise": "^3.3.1",
      "isomorphic-fetch": "^2.2.1"
    }
  }
  </code></pre>
  
  <p>This is the file where I build the UI:</p>
  
  <p>main.jsx</p>
  
  <pre><code>import React from 'react';
  import ReactDOM from 'react-dom';
  import 'isomorphic-fetch';
  import 'es6-promise';
  
  class Person extends React.Component {
  
    constructor(props){
      super(props);
      this.state = {people : []};
    }
  
    componentWillMount(){
      fetch('xxx/people',
        method: 'get',
        headers: {'token' : 'xxx'}
        )
        .then((response) =&gt; {
          return response.json()
        })
        .then((people) =&gt; {
          this.setState({ people: people })
        })
    }
  
    render(){
      return &lt;div&gt;
          &lt;input type="text" value={this.state.people[0].name}&gt;&lt;/input&gt;
        &lt;/div&gt;
    }
  }
  
  ReactDOM.render(
    &lt;Person/&gt;,
    document.getElementById('container')
  );
  </code></pre>
  
  <p>If I try to run it through the browser it fails (fetch method is not defined) I have also checked this releated post <a href="https://stackoverflow.com/questions/36484156/es6-fetch-is-undefined">ES6 `fetch is undefined`</a> and I have included the import with no success. I also included es6-promise import but it fails too.</p>
  
  <p>What am I doing wrong? Is it a config problem or what? When I run 'npm run build' there is no error and the build.js seems to be ok.</p>