Ensure that private key is shredded when removing an onion service

src/freedombone-utils-onion

         fi
     fi
     if [ -d /var/lib/tor/hidden_service_${onion_service_name} ]; then
+        shred -zu /var/lib/tor/hidden_service_${onion_service_name}/*
         rm -rf /var/lib/tor/hidden_service_${onion_service_name}
     fi
     systemctl restart tor