Add article title to RSS items

This handles the Haskell part of this (pretty sure it does, anyway).
We'll still need to update the blog or the coffeescript to actually get
the title so that this all works.
Our original thinking was that this was a unique key for the article. It needn't be a URL. But I think our own javascript is pulling it as the URL (vs our clients deciding what to send), so I agree, that probably makes sense as a rename to avoid confusion since we're not using the generality at all anyway.