Cupcake upgrades

[placeholder until merge-ready]
This pattern of chaining promises is missing parallel execution functionality.
Feel free to swap out Promiz micro with the full [Promiz library](https://github.com/Zolmeister/promiz), with `.all()` support which makes this code look like this:

```js
return Promiz.resolve(_.map(config.cupcakeSprites.svgOptions, function(opt, index) {
  var items = opt.items;
  var file = opt.file;
  return getCupcakeSVG({
             width: config.cupcakeSprites.width,
             height: config.cupcakeSprites.height,
             items: items
           }, file).then(function(cupcakeUri) {
        game.svgs.cupcakes[index] = cupcakeUri
        game.loadProgress += 1
      })
  }))
.all()
.then(function(){
game.state.start('setup')
})
```