Add /var/log/rsyncd.log stateful path

Corrects issue in a standalone swift image where
/mnt/state/var/log/rsyncd.log was not created since it had not been
registered as a stateful path.  On a controller+swift image, this issue
does not exist because other elements have registered /var/log (such as
mysql).

Change-Id: I658b133b74740dfb4c991cda9747e98c7bf6e2b3
Merge "Add /var/log/rsyncd.log stateful path"