Better integration with consolidate.js supported engines

[doup]

Right now the plugin has been written with Jade in mind. Handlebars (see #3), Mustache… and other don't work out of the box.

Fix and document.

Most popular ones:

• [ ] https://github.com/jadejs/jade 9522
• [ ] https://github.com/wycats/handlebars.js/ 9325
• [ ] https://github.com/janl/mustache.js 8529
• [ ] https://github.com/twitter/hogan.js 4223
• [ ] https://github.com/tj/ejs 2476
• [ ] https://github.com/olado/doT 2421
• [ ] https://github.com/mozilla/nunjucks 2348
• [ ] https://github.com/linkedin/dustjs 2062

Extra:

• [ ] https://github.com/facebook/react 31537
• [ ] https://github.com/jashkenas/underscore 16450
• [ ] https://github.com/lodash/lodash 11956