Add res.unauthorized() to 0.10 and fix issue with sails not defined in res.serverError

Here's #1037 for 0.10 - I noticed that it's still missing it. I hope I didn't miss any places where it's being loaded/used or anything. Thing have changed a lot internally since 0.9.7.

Also, it fixes an issue where serverError will throw a `ReferenceError: sails is not defined` when `sails.config.globals.sails = false`.