Fixed vertex normals and UVs for CircleGeometry

UVs were upside down and vertex normals needed a sign flip. Looks good now.

![Screen Shot 2013-04-08 at 1 56 01 AM](https://f.cloud.github.com/assets/1000017/350236/168322c2-a011-11e2-8c3a-70c2715f00b6.png)