Mustache, not handlebars.

It seems that handlebars is something that sits on top of mustache, but in any case I found this confusing from the perspective of a non-ruby-programmer.

By the way, I just went through the process of building a little [onebox](https://github.com/matsen/onebox/tree/pubmed) for [pubmed](http://www.ncbi.nlm.nih.gov/pubmed/), the canonical database of the biological literature. If you are interested, I will be sending on a pull request once it's finalized.