code: function getBabelConfig(env) {
    var babelrcPath = path.join(__dirname, '.babelrc')
    var babelrc = JSON.parse(fs.readFileSync(babelrcPath))
    babelrc.presets = resolve(
      babelrc.presets.map(preset => 'babel-preset-' + preset)
    )
    if (!babelrc.plugins) babelrc.plugins = []
    return babelrc
  }
docs: get babel config
  
  @param  {String} env
  @return {Object} babel config