Add layouts and posts for plugins.

@tristen @aaronlidman either of you want to adopt this promising young branch?

![](https://dl.dropboxusercontent.com/s/o5v9ypajdnoqido/2014-01-15%20at%2011.33%20AM%20%281%29.png)

* [x] Actually build out the CDN scripts and collect the right dist files: https://github.com/mapbox/mapbox.js-plugins/issues/2
* [x] Add links to documentation
* [ ] Visual cleanup?
* [x] Choose and 'curate' this selection of plugins.