title: Backbone.history.start() issue
body: <p>I'm trying this easy code from Addy's book but I can't make it work:</p>
  
  <pre><code>var TodoRouter = Backbone.Router.extend({
       routes: {
         "about" : "showAbout",
         "search/:query" : "searchTodos",
         "search/:query/p:page" : "searchTodos"
       },
       showAbout: function(){},
       searchTodos: function(query, page){
           var page_number = page || 1;
           console.log("Page number: " + page_number + " of the results for todos containing the wo");
          }
      });
  
      var myTodoRouter = new TodoRouter();
  
      Backbone.history.start();
  </code></pre>
  
  <p>The console returns this with an error:</p>
  
  <pre><code>Uncaught TypeError: Property '$' of object #&lt;Object&gt; is not a function backbone-min.js:1
  h.extend.start backbone-min.js:1
  (anonymous function)
  </code></pre>
  
  <p>If I comment out Backbone.history.start() there's no error (neither the "app" behaves the way it is supposed to behave).</p>
  
  <p>Any help is appreciated.</p>