Documentation spike

I've started trying to get docs added to the site.  While we don't need docs before launching the new site, I'd kinda like docs on the site before we make a big announcement about it or at least before 3.2 is released.

To generate these docs, here's what I ran from an rspec-core checkout:

```
$ bundle exec yard doc --no-cache -o ../rspec.github.io/source/documentation/3.2/rspec-core
```

(Note that rspec.github.io is in a sibling directory here).


This generated all the necessary files, but I'm seeing some issues.

First, if I go to http://localhost:4567/documentation/3.2/rspec-core, it's lacking all css/js assets:

![screen shot 2014-11-03 at 4 59 25 pm](https://cloud.githubusercontent.com/assets/49391/4893181/df3e135e-63bd-11e4-8d26-3e97d6f172bd.png)

...but if I go to http://localhost:4567/documentation/3.2/rspec-core/index.html, it does have the css/js assets:

![screen shot 2014-11-03 at 5 00 41 pm](https://cloud.githubusercontent.com/assets/49391/4893187/09dc8460-63be-11e4-9ebc-8eee8db44ce2.png)

I don't understand why the `/index.html` is needed.  (Obviously, I don't understand middleman well yet...)

On that apparently working page, I can't actually navigate to any of the docs -- it can't find the index files:

![screen shot 2014-11-03 at 5 02 33 pm](https://cloud.githubusercontent.com/assets/49391/4893205/4bf098c8-63be-11e4-92af-d86778b88b1d.png)

The result is the same for "Method List" and "File List".

Looking at the build directory, I notice I'm not seeing any of these files being copied there.  I suspect that's the culprit.

@JonRowe, do you have any ideas how to get this to work?