@dzucconi: Wire up saving an article

This wires it up so that you can save (POST/PUT) articles. There's some odd bootstrapping code necessary to work with HAL here that I'll comment on inline. I haven't written tests for it yet b/c I think it's something that can be extracted into halbone, but I'd rather get this up first.

![image](https://cloud.githubusercontent.com/assets/555859/4499528/c78394c6-4a83-11e4-8230-8ffde6c90a3b.png)
To explain the first example (requests needed to save an existing article given we crawl links client & server in an attempt to simplify code)...

**Server**
````coffeescript
spooky.get Article, 'article', params: { id: req.params.id }, (err, article) ->
  res.render article: article
````
1. GET /api — Request root endpoint
2. GET /api/articles/:id — Follow "article" link to get some data and render initial page load

**Client**
````coffeescript
spooky.get Article, 'article', params: { id: sd.ARTICLE.id }, (err, article) ->
  new EditView article: article
````
1. GET /api — Request root endpoint
2. GET /api/articles/:id – Follow "article" link to retrieve `_links.self` and inject url
3. POST /api/articles/:id — We click save and make an `article.save()`

Granted we could use [Traverson's POST/PUT/PATCH API](https://github.com/basti1302/traverson#post-put-delete-and-patch) to make the save directly and avoid step 2. However, that would involve some serious trickery and most likely an `if article.isNew() then #... else #...`—which defeats the whole purpose of taking that route in the first place.

I guess what I'm discovering here is strictly using HAL server or client is much easier than sharing between the two. For instance we could avoid the redundant fetches on the server if we only rendered/fetched data on the client and vice versa.

Ultimately though, I definitely do agree—simplicity > performance and the extra requests are better than nasty bootstrapping logic. In this case I just wanted to lay it out first before I think about a more elegant way to abstract it under a library like halbone.