title: Webpack ProvidePlugin vs externals?
body: <p>I'm exploring the idea of using <a href="http://webpack.github.io/" rel="noreferrer">Webpack</a> with <a href="http://backbonejs.org/" rel="noreferrer">Backbone.js</a>.</p>
  
  <p>I've followed the quick start guide and has a general idea of how Webpack works, but I'm unclear on how to load dependency library like jquery / backbone / underscore.</p>
  
  <p>Should they be loaded externally with <code>&lt;script&gt;</code> or is this something Webpack can handle like RequireJS's shim?</p>
  
  <p>According to the <a href="http://webpack.github.io/docs/shimming-modules.html" rel="noreferrer">webpack doc: shimming modules</a>, <code>ProvidePlugin</code> and <code>externals</code> seem to be related to this (so is <code>bundle!</code> loader somewhere) but I cannot figure out when to use which.</p>
  
  <p>Thanks</p>