xxl-tx

1.update and add(wait_workload_to_stop,stop_data_collecters,chkpoint_to_log,check_vdbench_pgrepstop_workload). 2.delete a "for" cycle for sleep and "waittime" parameter in Run() method and replace the "print" output to be log output. @ningli16 Signed-off-by: Lu Lu

Updated wait_workload_to_stop and stop_workload and Add new method to check vdbench @ningli16