Add High Res favicon for Retina displays.

src/views/index.jade

@@ -7,6 +7,7 @@ html(class="no-js", lang="")
     meta(name="description", description=description)
     meta(name="viewport", content="width=device-width, initial-scale=1")
     link(rel="apple-touch-icon", href="apple-touch-icon.png")
+    link(rel="icon", type="image/png" sizes="32x32", href="favicon-32.png")
     style#css!= css
   body
     #app!= body