Updated color palette for white backgrounds.

An updated color palette that looks great on white backgrounds.

![screen shot 2014-06-10 at 5 09 23 pm](https://cloud.githubusercontent.com/assets/220979/3237062/a2d8fce6-f0e3-11e3-9719-4fbb1013bd72.png)

Fixes https://github.com/visionmedia/debug/issues/112