More available archive check for rsync case (#770)

* This check for archive_is_available is more reliable than ICMP ping as many ISPs block that traffic but don't block ssh traffic

* force 1 second timeout so we don't block

run/rsync_archive/archive-is-reachable.sh

@@ -2,4 +2,4 @@
 
 ARCHIVE_HOST_NAME="$1"
 
-ping -q -w 1 -c 1 "$ARCHIVE_HOST_NAME" > /dev/null 2>&1
+ssh -q -o ConnectTimeout=1 "$RSYNC_USER"@"$ARCHIVE_HOST_NAME" exit