title: Webpack UglifyJS still giving warning messages
body: <p><a href="https://stackoverflow.com/questions/35456949/a-lot-of-warnings-with-webpack-uglify">A lot of warnings with webpack uglify</a></p>
  
  <p>I've turned off warnings in UglifyJS, but I'm still getting a few warnings from webpack.</p>
  
  <pre><code>WARNING in main-0.2.8.js from UglifyJs
  Dropping unused variable e [./~/bluebird/js/browser/bluebird.js:29,292]
  Dropping unused variable o [./~/bluebird/js/browser/bluebird.js:29,292]
  Dropping unused variable i [./~/bluebird/js/browser/bluebird.js:29,292]
  Non-strict equality against boolean: == false [./~/aurelia-pal-browser/dist/commonjs/aurelia-pal-browser.js:200,0]
  Non-strict equality against boolean: == false [./~/aurelia-pal-browser/dist/commonjs/aurelia-pal-browser.js:208,0]
  </code></pre>
  
  <p>Plugins from webpack.config</p>
  
  <pre><code>  plugins: [
      new AureliaWebpackPlugin(),
      new HtmlWebpackPlugin({
        title: 'Aurelia webpack skeleton - ' + pkg.version,
        template: 'index.prod.html',
        filename: 'index.html'
      }),
      new ProvidePlugin({
        $: 'jquery',
        jquery: 'jquery',
        "windows.jquery": 'jquery'
      }),
      new webpack.optimize.UglifyJsPlugin({
        compress: {
          warnings: false
        }
      })
    ]
  </code></pre>
  
  <p>If someone knows how to get rid of those last few warnings that would be nice.</p>