Add support for interfacing with a template or DOM fragment

[bruth]

Currently only one binding can be setup at a time, but it would be very useful to something like:

template = '<div class="book">
    <h1 role="title"></h1>
    <em role="author"></em>
    <p role="summary"></p>
 </div>'

fragment = $(template)

model = new Backbone.Model
    title: 'Secrets of a JavaScript Ninja'
    author: 'John Resig'
    summary: 'Learn to be a true JavaScript ninja like John..'

fragment.observe model

[alanchrt]

This would be a great next step. If it could stay de-coupled from the template engine and allow somehow for both DOM (Angular/rivets-style) and string templates (Handlebars, Underscore, etc), it would be truly amazing.