Simple angular app - Shopping website
I noticed that you have a spot for controllers, but then in your directive you declare a function for the Controller Attribute instead of using a controller that you have already at your disposal from the controller's section.  

I would think that you would want to be able to reuse that function that controls tab selection, you should create a controller for that so that you can reuse it on several pages, rather than write from scratch every time you create a page with Panel tabs.