title: Importing slick carousel theme css throws errors on webpack build
body: <p>I'm trying to import <code>slick-theme.scss</code> in my parent scss as </p>
  
  <p><code>@import "../node_modules/slick-carousel/slick/slick-theme.css";</code></p>
  
  <p>but during bundle, I get errors on the files imported in <code>slick-theme.scss</code>. Here's the error log</p>
  
  <pre><code>ERROR in ./node_modules/css-loader!./node_modules/postcss-loader/lib!./node_modules/sass-loader/lib/loader.js!./sass/app.scss
      Module not found: Error: Can't resolve './ajax-loader.gif' in '/Users/Vishal/Documents/Work/nf-core/sass'
       @ ./node_modules/css-loader!./node_modules/postcss-loader/lib!./node_modules/sass-loader/lib/loader.js!./sass/app.scss 6:89679-89707
  </code></pre>
  
  <p>I tried adding <code>resolve-url-loader</code> as well to the webpack configuration, but that doesn't help.</p>
  
  <p>Here's my webpack scss loader section</p>
  
  <pre><code>loaders: commonConfig.module.loaders.concat({
      test: /\.s?css$/,
      exclude: /(node_modules)/,
      use: ExtractTextPlugin.extract({
          fallback: 'style-loader',
          use: ['css-loader', 'postcss-loader', 'sass-loader']
      })
  })
  </code></pre>