core: update CONTRIBUTORS

Oh, it was a sorted list..

CONTRIBUTORS

@@ -19,6 +19,7 @@ François Cardinaux <fcardinaux@gmail.com>
 Grzegorz Junka <list1@gjunka.com>
 Hans-Christian Espérer <hc-git@hcesperer.org>
 Igor Goryachev <igor@goryachev.org>
+Jarimatti Valkonen <jarimatti@me.com>
 Jason Tanner <jt4websites@googlemail.com>
 Jim Geovedi (xyn on github)
 Kim Shrier <kim@westryn.net>
@@ -40,4 +41,3 @@ Steve Strong <srstrong@gmail.com>
 Tim Benniks <tim@timbenniks.nl>
 Tom Bradley <tom@71squared.com>
 Watt Poosanguansit <wpoosanguansit@yahoo.com>
-Jarimatti Valkonen <jarimatti@me.com>