Added Gunnlaugur Thor Briem to AUTHORS

AUTHORS

@@ -34,3 +34,4 @@ Ordered by date of first contribution:
   Honza Kral <honza.kral@gmail.com>
   Jonas Haag <jonas@lophus.org>
   Armin Ronacher <armin.ronacher@active-4.com>
+  Gunnlaugur Thor Briem <gunnlaugur@gmail.com>