Feature node badges

This is all kind of barebone, waiting for White October's layouts, but the core functionality should be there:

* nodes can be accessed via urls like http://www.dev/nodes/:slug
* js badges can be accessed via urls like http://www.dev/nodes/:slug/badge.js
* embeddable badges can be accessed via urls like http://www.dev/nodes/:slug/badge (or badge.html)

### TODO

I suppose we'll still need a pop-up explanatory blurb in the fashion of what we had on the certificates site. 
That will be easier though once the templates are available.