put svn.wikimedia.org behind misc. varnish

- add antimony as backend for svn in misc Varnish template
 (antimony is already defined as a backend in role/cache.pp)


needs a DNS change (Change-Id: I6d180559ea471) to go with it

Change-Id: I1d08b67621bbcac8a08110b8ddd96e4451feee91
Merge "put svn.wikimedia.org behind misc. varnish" into production