Flex menus

Hey, I've been working on getting this menu system set up where you can add more than just pages to a menu. I've got it to the point where you can configure it to accept any refinery file type (pages, blog posts, resources, etc) as well as make links to custom URLs. Here are some screenshots to get the idea across:

Edit Page:
![Edit Page](https://dl.dropbox.com/s/1flvwurjykb7p9i/Refinery%20Menu%20Edit.png)
If you're familiar with wordpress, you'll see where I got the inspiration :)

Tree Index Page:
![Index Page](https://dl.dropbox.com/s/9yvqekatnzmi2cm/Refinery%20Menu%20Sort.png)

I think the biggest question is whether you want to extend your gem to include this functionality, or you think this is better suited as its own extension. I'm happy either way!