Display version only if it is defined
Highlight request/response examples

Adds a Handlebars helper that highlights request/response examples
using Highlight.js.

The helper uses automatic language detection, but could be modified to
detect it based on the object's media type.

The template includes the GitHub theme by default; here is a demo of
all the bundled themes: <http://highlightjs.org/static/test.html>.
Merge pull request #8 from benwebber/highlight-examples

Highlight request/response examples