Add Favicon to the site

Same as the main GitLab.com site

app/views/layouts/application.html.erb

@@ -9,6 +9,9 @@
   <%# Viewport meta tag %>
   <meta name="viewport" content="width=device-width">
+  <%# Favicon %>
+  <link rel="shortcut icon" href="/favicon.ico" />
+
   <%= stylesheet_link_tag    'application', media: 'all' %>
   <%= javascript_include_tag 'application' %>
   <%= javascript_include_tag 'https://www.google.com/jsapi' %>