Updated logo to look less blurry at small size.

Removed triangle outlines (which were a bug), thinned bottom line
to look better against a black background. Removed an ugly gray
seam between the penguin's white front and yellow feet.

Added a raster version of roughly the same size as the one currently used at boot.

Before 
![screenshot](https://cloud.githubusercontent.com/assets/3179832/4268946/44321316-3cb6-11e4-8a57-475e3a461dfc.png)

After
![5694b096-3cb5-11e4-9d75-f5f34b0418be](https://cloud.githubusercontent.com/assets/3179832/4268955/60193898-3cb6-11e4-9036-84b73c362457.png)