@dzucconi (cc @dylanfareed): Initial wire up to Spooky

This starts to wire up Positron to Spooky. I've copy & pasted a lot of code from your [Force PR](https://github.com/artsy/force/pull/1272), so thanks for that.

I don't think I know enough about HAL yet to understand how to take advantage of it. Right now it seems like we're just going through the extra effort to override parse to ignore the `_links` and such. Maybe there's a way to write an adapter that better takes advantage of the automatic-crawling/not-hardcoded-urls ideas of HAL. Lemme know if you have any thoughts.

As a side note I've briefly looked at these which may be of use:
https://github.com/mikekelly/backbone.hal
https://github.com/basti1302/traverson
https://github.com/weluse/hyperagent

Still TODO: Write tests for the article/section models, which I will try to loop into my next PR.

![image](https://cloud.githubusercontent.com/assets/555859/4311152/6d0e3042-3eac-11e4-986c-029834e37a2a.png)
You're only considering the simple URL case, what about URLs such as artworks by an artist that are published? `/api/artworks?artist_id=...&published=true`. In HAL you can call that link `published_artworks` and make it a link on an Artist HAL+JSON response. So you don't need to actually know the structure of this URL to get published artworks by an artist.

API changes obviously need to either not happen or happen with full awareness :)

The ObjectiveC code is annoying. Every time I want to get something from the API I have to add 2 methods (a method that gets the data and another that expands parameters) and a property (the URL itself). With HAL none of that code needs to be written at all. Less code = better.