Inject webpack assets instead of hardcoding them in the template

[insin]

Investigate using inject: true to insert webpack assers before </body> - the current template hardcodes them, resulting in 404s for everything but app.js when running webpack on the server.

This should also preserve the correct ordering of dependencies, as html-webpack-plugin inserts entry assets last.

[insin]

Defaulting to public/index.html allowed us to:

1. Not have to decide where the HTML gets generated in, because it's static
2. Make it easy for people to use static assets by putting them in the public/ directory

Guess we need to make some decisions now

[insin]

inject is now enabled by default in html-webpack-plugin@2