[#19,routing][xs]: move history out to external calling code as we need to be able to reload the app (e.g. to change data source).

demo/js/app.js

@@ -7,6 +7,7 @@ $(function() {
     el: window.$container
     , model: dataset
   });
+  Backbone.history.start();
   setupLoadFromWebstore(function(dataset) {
     window.dataExplorer.remove();
     window.dataExplorer = null;

src/view.js

@@ -98,7 +98,6 @@ my.DataExplorer = Backbone.View.extend({
 
     this.router = new Backbone.Router();
     this.setupRouting();
-    Backbone.history.start();
 
     // retrieve basic data like headers etc
     // note this.model and dataset returned are the same