Feature copy and polish

This is a significant style update. It adds feature copy to the homepage, as well as icons, a rouge highlighting theme, and a logo I've been working on. When you review, I'd boot it up to see it live which will obviously give you a far different look than just browsing the changes.

At this point, the things I think I have left to do are:
- [ ] Prepare for heroku (something always breaks so I have to figure out what that thing is)
- [ ] Sanitize the input that goes from the textarea to Rouge
- [ ] Wrap that all up in a parser class with error handling and the like

Anything else you can think of? I would also like to transfer / style the readme from Rouge to the website so people can get up and running without going to the github page, but I don't see that as strictly necessary.
I'm just waiting until you upload the latest rouge to ruby gems since I [started using](https://github.com/jneen/rouge.jneen.net/pull/4/files#diff-127a850b7d7b20173ad3fba88f8a25e3R4) the lexer titles. I have 100% intention of switching it back for release for exactly the reason you mentioned.