Move scap source location from fenari to tin

Have the scap source locally on tin instead of on NFS. This should make
it faster.

Not being on NFS means cron jobs on hume can't access
/home/wikipedia/common anymore. That's not really a problem since it's
already a scap target, the scripts just need to be updated to use
/usr/local/apache/common ($MW_COMMON) instead of /home. Many cron jobs
were doing the right thing already.

Made tin be the primary rsync server for the MW source, instead of nfs1.

Coexisting with git-deploy on tin is a bit awkward since it conflicts
with the migration plan we had assumed during the development of the
git-deploy manifests. Just remove the class that creates the conflicting
mw-deployment-vars.sh for now.

Use dsh instead of ddsh, since ddsh is an unpuppetized hack.

Change-Id: I9d315c4cb937389fb881535816a73827db5933cb