Fix samba usershares permissions
Setting the group ownership of /var/lib/samba/usershares/ to "students" fails during the installation because this group is defined in LDAP and the slapd is not running at the time the samba promise bundle is evaluated. Thus use the numeric GID instead. The group is defined in ldap-bootstrap/{samba.ldif,gosa.ldif}. Closes: #1039461.
Edited by Guido Berhörster