svn services changes

As mentioned in centos-5-machines-upgrading-to-5-6 CentOS machines have upgraded. They now run svn 1.6.11, so the svn-1-6-6-serv service is being withdrawn.

svn has problems if used on machines with different versions, as it silently upgrades the local copy, meaning that older versions may be unable to use it. Some people had problems with the version on the slogin-serv machines so a special server svn-1-6-6-serv was setup. All the users which reported problems have confirmed that the new CentOS svn satisfies their requirements, so the special server will soon be shutdown unless anyone contact sys-admin soon.