add Konstantinos Koukopoulos to CONTRIBUTORS.txt

Also setting new record for longest contributor name.

CONTRIBUTORS.txt

@@ -168,3 +168,4 @@ Tadej Janež, 2014/08/08
 Akexander Koshelev, 2014/08/19
 Davide Quarta, 2014/08/19
 John Whitlock, 2014/08/19
+Konstantinos Koukopoulos, 2014/08/24