title: css-loader not importing .css file returning empty object
body: <p>Importing style from css files. Returning empty object. Seems css-loader is not working correctly. Can anyone help me on this. Please find the reference files below</p>
  
  <p><strong>index.js</strong>
  </p>
  
  <pre><code>import React from 'react'   
  import style from './header.css'
  
  console.log(style) // Returning empty object
  
  export default class Header extends React.PureComponent {
    render() {
      return(
        &lt;header className = {style.header}&gt;
          This is header component
        &lt;/header&gt;
      )
    }
  }
  </code></pre>
  
  <p><strong>./header.css</strong>
  </p>
  
  <pre><code>.header {
    background: #007DC6;
  }
  </code></pre>
  
  <p><strong>./webpack.config.js</strong>
  </p>
  
  <pre><code>{
    test: /\.css$/,
    exclude: /node_modules/,
    loaders: ['style-loader', 'css-loader'],
  }, {
    test: /\.css$/,
    include: /node_modules/,
    loaders: ['style-loader', 'css-loader'],
  }
  </code></pre>