old_contents: var webpack = require('webpack');
  
  module.exports = {
    module: {
      loaders: [
        { test: /\.js$/, loaders: ['babel-loader'], exclude: /node_modules/ }
      ]
    },
    output: {
      library: 'ReactProps',
      libraryTarget: 'umd'
    },
    resolve: {
      extensions: ['', '.js']
    }
  };
  
new_contents: var webpack = require('webpack');
  
  module.exports = {
    module: {
      loaders: [
        { test: /\.js$/, loaders: ['babel-loader'], exclude: /node_modules/ }
      ]
    },
    output: {
      library: 'ReactProps',
      libraryTarget: 'umd'
    },
    externals: {
      'react': {
        root: 'React',
        commonjs2: 'react',
        commonjs: 'react',
        amd: 'react'
      }
    },
    resolve: {
      extensions: ['', '.js']
    }
  };
  
subject: update webpack.config