package/debian: updated changelog to mention all released versions.

package/debian/changelog

@@ -1,5 +1,17 @@
-magnum (1.0) UNRELEASED; urgency=low
+magnum (2015.05-1) unstable; urgency=low
 
-  * Latest upstream version
+  * Version 2015.05
+
+ -- Vladimír Vondruš <mosra@centrum.cz>  Sat, 09 May 2015 11:43:43 +0200
+
+magnum (2014.06-1) unstable; urgency=low
+
+  * Version 2014.06
+
+ -- Vladimír Vondruš <mosra@centrum.cz>  Mon, 30 Jun 2014 01:21:04 +0200
+
+magnum (2014.01-1) unstable; urgency=low
+
+  * Version 2014.01
 
  -- Vladimír Vondruš <mosra@centrum.cz>  Fri, 31 Jan 2014 12:20:58 +0100