FIX: last ip address could point at wrong ip

Due to unicorn env object recycling request.ip could point at the wrong
ip address by the time defer block is called. This usually would happen
under load.

This also avoids keeping the entire request object as referenced by the
closure.

lib/auth/default_current_user_provider.rb

@@ -118,9 +118,11 @@ class Auth::DefaultCurrentUserProvider
 
     if current_user && should_update_last_seen?
       u = current_user
+      ip = request.ip
+
       Scheduler::Defer.later "Updating Last Seen" do
         u.update_last_seen!
-        u.update_ip_address!(request.ip)
+        u.update_ip_address!(ip)
       end
     end