Add nunjucks example

[jlongster]

Hey,

You can find code for integrating it here: http://nunjucks.jlongster.com/home#Express

It basically looks like this:

var nunjucks = require('nunjucks');
var express = require('express');

var env = new nunjucks.Environment(new nunjucks.FileSystemLoader('views'));
env.express(app);

You pass the path of your templates to the FileSystemLoader. You can ignore all the app.set("views") crap and other settings.

[ralyodio]

not sure how this will work with current app.js layout.