Upgrade Slate sample to Slate 1.5

Closes gh-361

samples/rest-notes-slate/slate/source/javascripts/app/_lang.js

@@ -1,3 +1,5 @@
+//= require ../lib/_jquery
+
 /*
 Copyright 2008-2013 Concur Technologies, Inc.
 
@@ -28,9 +30,11 @@ under the License.
     $(".lang-selector a").removeClass('active');
     $(".lang-selector a[data-language-name='" + language + "']").addClass('active');
     for (var i=0; i < languages.length; i++) {
-      $(".highlight." + languages[i]).hide();
+      $(".highlight.tab-" + languages[i]).hide();
+      $(".lang-specific." + languages[i]).hide();
     }
-    $(".highlight." + language).show();
+    $(".highlight.tab-" + language).show();
+    $(".lang-specific." + language).show();
 
     global.toc.calculateHeights();