Use some fenced code blocks

Hi there,

I thought I'd introduce some [fenced code blocks](https://help.github.com/articles/github-flavored-markdown#fenced-code-blocks) to make your `README.md` a little more readable:

|Before|After|
|---|---|
|![screen shot 2014-06-02 at 1 19 34 pm](https://cloud.githubusercontent.com/assets/121322/3152792/b67669a2-ea92-11e3-96b8-76847066f5ac.png)|![screen shot 2014-06-02 at 1 19 15 pm](https://cloud.githubusercontent.com/assets/121322/3152791/b6745b3a-ea92-11e3-9d90-c1846c9d7dd6.png)|

Cheers,
  Lee :beers: