skeleton: sync /etc/shadow with /etc/passwd

Synchronize /etc/shadow with /etc/passwd:
  - remove "halt" and "uucp"
  - add "sys", "mail" and "www-data"

Signed-off-by: Jérôme Pouiller <jezz@sysmic.org>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>

system/skeleton/etc/shadow

@@ -1,8 +1,9 @@
 root::10933:0:99999:7:::
-bin:*:10933:0:99999:7:::
 daemon:*:10933:0:99999:7:::
+bin:*:10933:0:99999:7:::
+sys:*:10933:0:99999:7:::
 sync:*:10933:0:99999:7:::
-halt:*:10933:0:99999:7:::
-uucp:*:10933:0:99999:7:::
+mail:*:10933:0:99999:7:::
+www-data:*:10933:0:99999:7:::
 operator:*:10933:0:99999:7:::
 nobody:*:10933:0:99999:7:::