Chase @trent's change in 390ccb4.

…d attributes.

h/t to @jclulow for pointing the [`skip-front-matter`](http://asciidoctor.org/docs/user-manual/#front-matter-added-for-static-site-generators)
attribute.

The `skip-front-matter` attribute can only be passed in via the CLI:

```sh
$ asciidoctor --attribute=skip-front-matter ...
```

Brought to you by: future self asking, "WTF isn't this the default behavior?"

RFD's are going to need their own ghpages branch and
joyent.github.io/rfd/rfd*.html needs to be a thing otherwise this won't
render well by default.  This is a start, and it improves the state
of the world.

…nal file.