Add German icons for edit toolbar

Icons created by [[de:User:Hk kng]] and released under public domain:
http://de.wikipedia.org/wiki/Bild:Button_kursiv.png
http://de.wikipedia.org/wiki/Bild:Button_fett.png

CREDITS

@@ -53,6 +53,7 @@ following names for their contribution to the product.
 
 == Translators ==
 * Anders Wegge Jakobsen
+* Hk kng
 * Hojjat
 * Meno25
 * Rotem Liss

languages/messages/MessagesDe.php

@@ -189,6 +189,11 @@ $dateFormats = array(
 	'ISO 8601 both' => 'xnY-xnm-xnd"T"xnH:xni:xns'
 );
 
+$imageFiles = array(
+	'button-bold'     => 'de/button_bold.png',
+	'button-italic'   => 'de/button_italic.png',
+);
+
 $messages = array(
 # User preference toggles
 'tog-underline'               => 'Links unterstreichen:',