[cluster] deploy: skip non-existing files

In "one-by-one" mode, test the existence of a file before to try to
transfer it.

cluster/cluster-deploy.sh

@@ -125,6 +125,10 @@ fi
 # ... or one by one
 for FILE in "$@" ; do
   echo "Deploying '$FILE'..."
+  if [ ! -e "$FILE" ] ; then
+    echo "This file doesn't exist, skipping."
+    continue
+  fi
   if [ "$RSYNC" = "1" ] ; then
     $PRSYNC -a $DELETE $LOGIN -h "$HOSTS" -- "$FILE" "$DEST_DIR"
   else