Update Ruby examples in README with codefencing

Using codefencing in the README we can update the examples from plain text to Ruby examples and it gives it a little more :sparkles: 

Before:

![image](https://f.cloud.github.com/assets/79995/1111417/27f5b7ea-19ab-11e3-8a90-3cb5e93dc359.png)

After:

![image](https://f.cloud.github.com/assets/79995/1111415/13772f56-19ab-11e3-9361-ff29da15f239.png)