Add announcement admin and view template

app/views/layouts/admin.html.erb

@@ -15,9 +15,11 @@
 <body>
 <div class="container">
   <div id ="nav" class="span-24">
+    <%= link_to 'Home', root_path %> |
     <%= link_to 'Pages', admin_pages_path %> |
     <%= link_to 'Snippet', admin_snippets_path %> |
-    <%= link_to 'Layout', admin_layouts_path %>
+    <%= link_to 'Layout', admin_layouts_path %> |
+    <%= link_to 'Announcement', admin_announcements_path %>
   </div>
   
   <%= yield %>