mate: remove major-ver and minor-ver

Keep only the version atribute in derivations, with the full version
string of the package. This will make it easier to write a script for
automatic updating of the packages using the update-source-version
command from common-updater-scripts.

pkgs/desktops/mate/caja/default.nix

@@ -2,12 +2,10 @@
 
 stdenv.mkDerivation rec {
   name = "caja-${version}";
-  version = "${major-ver}.${minor-ver}";
-  major-ver = "1.18";
-  minor-ver = "5";
+  version = "1.18.5";
 
   src = fetchurl {
-    url = "http://pub.mate-desktop.org/releases/${major-ver}/${name}.tar.xz";
+    url = "http://pub.mate-desktop.org/releases/${mate.getRelease version}/${name}.tar.xz";
     sha256 = "1ild2bslvnvxvl5q2xc1sa8bz1lyr4q4ksw3bwxrj0ymc16h7p50";
   };