example is not working with the last version of webpack (v2)

```
> webpack-dev-server --config webpack-config.js --hot --progress --colors --inline

Invalid configuration object. Webpack has been initialised using a configuration object that does not match the API schema.
- configuration has an unknown property 'debug'. These properties are valid:
object { amd?, bail?, cache?, context?, dependencies?, devServer?, devtool?, entry, externals?, loader?, module?, name?, node?, output?, performance?, plugins?, profile?, recordsInputPath?, recordsOutputPath?, recordsPath?, resolve?, resolveLoader?, stats?, target?, watch?, watchOptions? }
The 'debug' property was removed in webpack 2.
Loaders should be updated to allow passing this option via loader options in module.rules.
Until loaders are updated one can use the LoaderOptionsPlugin to switch loaders into debug mode:
plugins: [
new webpack.LoaderOptionsPlugin({
debug: true
})
]
- configuration.output.path: The provided value "./tmp" is not an absolute path!
- configuration.resolve.extensions[0] should not be empty.
```