make menu colors configurable for weird color schemes

Here's what I see when I load up the stream-adventure:

![screen shot 2013-09-17 at 10 32 28 am](https://f.cloud.github.com/assets/175515/1159150/4d4e7c4a-1fc1-11e3-8666-71ee1a9f63ce.png)

Oh no! Perhaps I have a weird color scheme, but the background isn't working at all for me. I like low-contrast text, which looks good except when it's a background. So, here I've added `--fg` (or `-f` if you prefer) and `--bg` (`-b`) options so you can run `stream-adventure --bg black` and have a readable background, as such:

![screen shot 2013-09-17 at 10 46 12 am](https://f.cloud.github.com/assets/175515/1159157/7bc8fea6-1fc1-11e3-80bf-4bb81601e892.png)

I can apply the same thing to the rest of the schools if you find this useful.