(WIP) Book IA - new Spice APIs

Fix for issue #955 - work in progress.

It obviously needs a lot of work on the graphic side, but this is the very first screenshot (desktop view) - just to show it works:
![schermata 2014-08-06 alle 21 10 51](https://cloud.githubusercontent.com/assets/3652195/3783724/24c446da-19b0-11e4-885c-092060705cbc.png)

I think in the final book tile layout should go title, author, number of pages and the total rating, plus review count, and in the detail view (which I still have to do) could be nice to have the critic's review, which right now it's randomly chosen between the available ones..

Let me know if you have suggestions :)

//cc @moollaza, @jagtalon, @chrismorast

@MariagraziaAlastra It's probably worth checking that `api_result` is defined, too:

```
if (!api_result || api_result.error) {
  return Spice.failed('book');
}
```