Inverting the colors of the favicon


I've been keeping the cheatsheet and the official docs open while I'm working. 

They both have the same favicon so it's easy to get them mixed up.

I took the color-inverted logo from the footer of the official laravel page and turned it into a favicon.  Makes it a lot easier to identify which page is which.

What do you think?

![favicon](https://f.cloud.github.com/assets/5303882/1698707/f4bd7c7e-5f5e-11e3-972b-3db6aa02d90d.png)