[WIP] Billable hours overview

Just starting out

![screen shot 2014-12-24 at 14 53 02](https://cloud.githubusercontent.com/assets/642544/5548882/cb5b9a50-8b7c-11e4-81ae-6dc3c22cb232.png)

fwiw to do normal text in haml you can just omit anything before the text, so:

```haml
- else
  all entries billed
```

It'll be localized eventually so doesn't really matter, just thought it was good to know ^^