title: Webpack relative path resolve error
body: <p>I'm importing a module like this <code>import { validate } from '../../_lib';</code>
  but webpack throws me an error <code>ModuleNotFoundError</code>. Looking inside it seems like it parses the path in a wrong why: <code>resolve file  c:/Users/Me/project/resource/func\\_lib doesn't exist</code></p>
  
  <hr>
  
  <p>My directory looks something like this:</p>
  
  <pre><code>project
   resource
    func
     file.js
  _lib
   validate.js
   index.js
  </code></pre>
  
  <p>in <code>validate.js</code> I'm exporting a func like this <code>export function validate(){}</code>
  and in <code>index.js</code> I'm exporting validate this way <code>export * from './validate'</code></p>
  
  <hr>
  
  <p>this is mt webpack config</p>
  
  <pre><code>var webpack = require('webpack');
  
  module.exports = {
    // entry: provided by serverless
    // output: provided by serverless
    target: 'node',
    externals: [
      'aws-sdk',
      'dynamodb-doc'
    ],
    resolve: {
      extensions: ['', '.js', '.jsx']
    },
    devtool: 'source-map',
    plugins: [
      new webpack.IgnorePlugin(/^\.\/locale$/, /moment$/),
      new webpack.optimize.DedupePlugin(),
      new webpack.optimize.OccurenceOrderPlugin(),
      new webpack.optimize.UglifyJsPlugin({
        compress: {
          unused: true,
          dead_code: true,
          warnings: false,
          drop_debugger: true
        }
      }),
          function () {
              this.plugin("done", function (stats) {
                  if (stats.compilation.errors &amp;&amp; stats.compilation.errors.length) {
                      console.error(stats.compilation.errors)
                      throw new Error(stats.compilation.errors);
                  }
              });
          }
    ],
    module: {
      loaders: [
              {
          test: /\.json$/,
          loader: 'json'
        },
        {
          test: /\.html$/,
          loader: 'html'
        },
              {
          test: /\.js$/,
          loader: 'babel',
          exclude: /node_modules/,
          query: {
            presets: ['es2015', 'stage-0']
          }
        }
      ]
    }
  };
  </code></pre>