Match comint mode colours with eshell.

Playing around with the theme, I like it a lot so far. I threw together a theme for [st](http://st.suckless.org/) in this [gist](https://gist.github.com/jcpetkovich/8049651).

I have a suggestion though, I think for consistency with eshell, comint-mode should get similar colours.

At current:

![green-comint](https://f.cloud.github.com/assets/159257/1788370/b7932c14-6926-11e3-9c3e-1ac03799abe8.png)

Vs with eshell's prompt colours:

![dark-comint](https://f.cloud.github.com/assets/159257/1788371/c4ea397a-6926-11e3-9aac-9d0f90ea75c3.png)