Add Fork me on GitHub banner

Here's what it looks like:

![screenshot from 2014-05-14 15 55 39](https://cloud.githubusercontent.com/assets/1847232/2978581/75ebceda-dbbb-11e3-8ef2-f4c030f7a1ef.png)

I added a link in the code with all available colors and orientations- not sold on this particular color or placement, but should be a good proof-of-concept to work off of.