firefox: add andir (myself) as maintainer

I have been working on this for some time now so it probably makes
sense...

pkgs/applications/networking/browsers/firefox/packages.nix

@@ -25,7 +25,7 @@ rec {
     meta = {
       description = "A web browser built from Firefox source tree";
       homepage = http://www.mozilla.com/en-US/firefox/;
-      maintainers = with lib.maintainers; [ eelco ];
+      maintainers = with lib.maintainers; [ eelco andir ];
       platforms = lib.platforms.unix;
       license = lib.licenses.mpl20;
     };