Fixed issue where run-workload was exiting with error code 0 when error occured

Change-Id: I0872fef9a16b19b4a8ac273c2f28a415eb3d1dc2
Reviewed-on: http://gerrit.sjc.cloudera.com:8080/4030
Reviewed-by: Taras Bobrovytsky <tbobrovytsky@cloudera.com>
Tested-by: jenkins