title: Less-Loader: Import URLs are being treated as relative URLs, without the --relative-url option being passed
body: <p>I'm trying to use the less-loader to load a less file with a url import at the top. This url import is for a file that is hosted elsewhere (on a cdn). </p>
  
  <p>app.less</p>
  
  <pre><code>@import url("http://cdn-name/mixins.less");
  </code></pre>
  
  <p>When I try to load this less file with the less-loader, I get the following error:</p>
  
  <pre><code>ERROR in ./~/css-loader!./~/less-loader!./static-content/less/app.less
  Module build failed: Cannot resolve 'file' or 'directory' ./http://cdn-name/mixins.less 
  </code></pre>
  
  <p>It appears that the less loader is treating my url import as a relative path, instead of actually detecting that it is its own url that contains a resource to be fetched.</p>
  
  <p>My webpack config looks like this:</p>
  
  <pre><code>module.exports = {
    entry: {
      bundle: ['./static-content/js/index.js'],
      vendor: ['react', 'react-dom']
    },
    output: {
      path: jsGeneratedPath,
      filename: 'bundle.min.js',
      publicPath: 'http://localhost:8444/assets/',
      hotUpdateChunkFilename: 'hot/js-update.js',
      hotUpdateMainFilename: 'hot/json-update.json',
      recordsPath: path.resolve(__dirname, '/assets/hot/')
    },
    stats: {
      colors: true,
      reasons: true
    },
    module: {
      preLoaders: [
        {
          test: /\.jsx?$/,
          loader: 'eslint-loader',
          exclude: /node_modules/
        }
      ],
      loaders: [
        {
          test: /.js?$/,
          loader: 'babel-loader',
          exclude: /node_modules/,
          progress: true
        },
        {
          test: /.less$/,
          loader: 'style!css!less',
          exclude: /node_modules/,
          progress: true
        }
      ]
    },
    plugins: [
      new webpack.optimize.CommonsChunkPlugin({
        names: ['vendor'],
        minChunks: Infinity,
        filename: '[name].min.js'
      })
    ]
  }
  </code></pre>
  
  <p>Any thoughts on why this might be happening? I think it <strong>might</strong> have something to do with the type of file I'm trying to import (a less file) because if I swap my import with a css file instead (hosted on one of google's CDNs for example) then the resolution happens fine.</p>
  
  <p>I've tried with and without quotes around the url.</p>
  
  <p>webpack v 1.13.1
  webpack-dev-server v 1.14.1
  less loader v 2.2.3 </p>