title: Image from Npm package not found in Webpack
body: <p>I am trying to use webpack with bxslider package from npm. 
  I have already installed all necessary packages. I get below error when I try to build. Seems like it is not able to find the image from the npm package. It does package js file but when I include css file it seem to not locate image file properly. </p>
  
  <p>Error message:</p>
  
  <p><strong>ERROR in ./src/scss/index.scss
  Module build failed: ModuleNotFoundError: Module not found: Error: Can't resolve './images/bx_loader.gif' in 'D:\Test'</strong></p>
  
  <p>Entry file:</p>
  
  <pre><code>import '../scss/index.scss';
  import 'bootstrap/js/dist/util';
  import 'bootstrap/js/dist/collapse';
  import 'bootstrap/js/dist/dropdown';
  import 'bootstrap/js/dist/tab';
  import 'bootstrap/js/dist/tooltip';
  import 'bxslider/dist/jquery.bxslider.min';
  import './main';
  </code></pre>
  
  <p>Webpack config file:</p>
  
  <pre><code>const path = require('path');
  const webpack = require('webpack');
  const ExtractTextPlugin = require( 'extract-text-webpack-plugin' );
  const theme_path = 'dist/wp-content/themes/theme-name/';
  module.exports = {
    mode: 'production',
    entry: {
      app: './src/js/index.js'
    },
    output: {
      filename: '[name].bundle.js',
      path: path.resolve(__dirname, theme_path + 'assets/js')
    },
    module: {
      rules: [
        {
          test: /\.js$/,
          exclude: /node_modules/,
          loader: 'babel-loader'
        },
        // Run Sass through loaders before bundling into `style.css`
        {
          test: /\.scss$/,
          enforce: 'pre',
          loader: ExtractTextPlugin.extract([
            {
              loader: 'css-loader',
              options: {
                minimize: true,
                sourceMap: true
              }
            },
            {
              loader: 'sass-loader'
            }
          ])
        },
        {
          test: /\.(png|svg|jpg|gif)$/,
          use: [
            'file-loader'
          ]
        }
      ]
    },
    plugins: [
      new ExtractTextPlugin('../css/main.css'),
      new webpack.ProvidePlugin({
        $: "jquery",
        jQuery: "jquery",
        Popper: ['popper.js', 'default'],
        Collapse: 'exports-loader?Collapse!bootstrap/js/dist/collapse',
        Dropdown: 'exports-loader?Dropdown!bootstrap/js/dist/dropdown',
        Tab: 'exports-loader?Tab!bootstrap/js/dist/tab',
        Tooltip: "exports-loader?Tooltip!bootstrap/js/dist/tooltip",
        Util: 'exports-loader?Util!bootstrap/js/dist/util'
      })
    ]
  };
  </code></pre>