Fix deletion on server

Previously random files were deleted on the ftp remote because the
requested list of files was not sorted. A simple sort by date is enough
in this case because the directories are already named according to the
date.

myftpdumper.sh

@@ -260,7 +260,7 @@ upload() {
 
         # FTP: delete old backups
         info "Delete old backups on FTP..."
-        ftpfiles=$(exec_ftp "cd \"$FTP_DIR\"; nlist; exit")
+        ftpfiles=$(exec_ftp "cd \"$FTP_DIR\"; nlist; exit" | sort)
         ## filter files starting with a dot
         ftpfiles=( $(echo $ftpfiles | sed 's,\.[A-Za-z0-9_\/\.]* , ,g') )
         ## find old backups