slim: Build with ConsoleKit support

pkgs/top-level/all-packages.nix

···
 
   dropbox = callPackage ../applications/networking/dropbox { };
 
-  slim = callPackage ../applications/display-managers/slim {
-    consolekit = null;
-  };
+  slim = callPackage ../applications/display-managers/slim { };
 
   sndBase = builderDefsPackage (import ../applications/audio/snd) {
     inherit fetchurl stdenv stringsWithDeps lib fftw;