FIX: stop sending a blank /favicon.ico

instead have nginx ship a 404 for it.

config/nginx.sample.conf

@@ -80,6 +80,13 @@ server {
     internal;
   }
 
+  # return a cheap 404 for favicon cause lots of browsers like asking for it
+  # view source and old browsers, this bypasses the rails stack at the expense of
+  # having an ugly 404 page
+  location /favicon.ico {
+    return 404;
+  }
+
   location / {
     root $public;
     add_header ETag "";