Add shakapacker

Author: justin808

app/views/pages/index.html.erb

@@ -1,6 +1,7 @@
 <h2>
   <%= link_to "Open Source example",
               "https://github.com/shakacode/react-webpack-rails-tutorial/" %> of using the <%= link_to "React on Rails gem", "https://github.com/shakacode/react_on_rails" %>
+  and the <%= link_to "Shakapacker gem", "https://github.com/shakacode/shakapacker" %>
 </h2>
 <h3>Using <%= link_to "Ruby on Rails", "http://rubyonrails.org/" %> with
   <%= link_to "Action Cable", "http://guides.rubyonrails.org/action_cable_overview.html" %> +