Status bar summary

![screen shot 2014-12-03 at 21 46 54](https://cloud.githubusercontent.com/assets/1850538/5288679/499f3e68-7b37-11e4-9555-53dee1cf3f9e.png)

So it display the number of errors/warning.

Let me know if you need further information about the commit.
You should only add the new element to the DOM once you've finished building it. 

Touching the DOM is slow, so try to avoid it when possible. Here it's easy - just build everything first, then add it in one go.