Fix terminal coloring issues

Here is what I was getting when I ran the initial `amigo` command. 
![screen shot 2013-10-31 at 6 25 50 pm](https://f.cloud.github.com/assets/809953/1451300/a0336e70-4294-11e3-8359-2071cf1219ba.png)

This is happening because the lib doesn't account for dark terminal backgrounds. Here is the result of the fix described in this PR.

![screen shot 2013-10-31 at 6 26 39 pm](https://f.cloud.github.com/assets/809953/1451302/b6569eca-4294-11e3-8afb-35d5ceacb284.png)