Compatibility with node 11, Babel 7 and webpack-dev-server

This is a major upgrade which includes:

• Fixed compatibility with node 11
• Removed webpack-serve replacing with webpack-dev-server
• All packages upgraded to latest

Breaking change:

• You'll need to export default your express httpServer object instead of setting module.exports like so:

// OLD
const httpServer = app.listen(PORT, () => {
  console.log(`Example app listening at ${PORT}...`);
});
module.exports = httpServer;

// NEW
export default app.listen(PORT, () => {
  console.log(`Example app listening at ${PORT}...`);
});