Hiring as a Service

This is a work-in-progress for https://github.com/npm/newww/issues/172. Using the the [hbsfy browserify transform](https://github.com/npm/newww/blob/54b683a44810586c36655644f8c48dbd4219f4f4/package.json#L19-L22), we can now use our handlebars templates browser-side! See the [xhr thingy](https://github.com/npm/newww/blob/54b683a44810586c36655644f8c48dbd4219f4f4/assets/scripts/hiring.js) and the [template](https://github.com/npm/newww/blob/54b683a44810586c36655644f8c48dbd4219f4f4/assets/templates/hiring.hbs).

Remaining work:

- Put `#hiring-container` elements on pages where we want to render hiring widgets
- Use data attributes instead of overloading a DOM id
- Use multiple data attributes to configure things like number of results to fetch and display
- Render the full list at /whoshiring
- Remove all the old server-side who's hiring stuff