Spruce up shell.html

Made a bunch of changes to shell, including a logo, a nicer spinner, and
better colors. Note on the image: I simply inlined the svg logo from
docs/, which made the file significantly longer(but hey, it looks nice).
![untitled](https://f.cloud.github.com/assets/4681820/2156229/dcc7076c-9455-11e3-911e-b64aa429d0e0.png)