Add a logo

I really like the library and the name, so I spent some time working on a logo concept.
Feedback, especially the constructive kind, is most welcome. 

![screen shot 2014-11-21 at 11 13 36 pm](https://cloud.githubusercontent.com/assets/519433/5150669/f6af08b6-71d4-11e4-8cb4-59dbd029e84a.png)

![screen shot 2014-11-21 at 11 18 00 pm](https://cloud.githubusercontent.com/assets/519433/5150700/34d03a20-71d5-11e4-9162-5a3b6d57bd4f.png)

A few other concepts that I tried but ditched for various reasons (mostly looking too similar to other symbols/flags/letters)

![screen shot 2014-11-21 at 11 15 52 pm](https://cloud.githubusercontent.com/assets/519433/5150739/a0d2bfc2-71d5-11e4-9b7c-c3a77cf213f5.png)