Add Stas Rudakou to CONTRIBUTORS.txt

CONTRIBUTORS.txt

@@ -134,3 +134,4 @@ Romuald Brunet, 2013/03/29
 Aaron Harnly, 2013/04/04
 Peter Brook, 2013/05/09
 Muneyuki Noguchi, 2013/04/24
+Stas Rudakou, 2013/05/29