title: Webpack.config not running Sass-Loader before PostCSS-Loader
body: <p>My config file currently has the following possibly relevant code:</p>
  
  <pre><code>  {
      // do not exclude `node_modules`
      test: /\.css$/,
      loader: ExtractTextPlugin.extract(
        'style-loader',
        'css',
        { publicPath: '../' }
      )
    },
    {
      test: /\.scss$/,
      exclude: /node_modules/,
      loader: ExtractTextPlugin.extract(
        'style-loader',
        ['css-loader', 'postcss-loader', 'sass-loader'],
        { publicPath: '../' }
      )
    },
  </code></pre>
  
  <p>It's important that I run sass-loader first because PostCSS-loader (Autoprefixer) is unable to reach code within a @mixin that I have.</p>
  
  <p>So far I've been unable to apply the relevant vendor prefix to the @mixin code being imported in. Everything works as expected if I move the @mixin code to where I @include it.</p>