Add sleep workload

Don't forget to set the new environment variable `HADOOP_JOBCLIENT_TESTS_JAR` in `hibench-config.sh`.
You can find sleep job in hadoop jobclient jar in MRv2, while in MRv1 sleep is in hadoop examples. Hence mark this configuration as YARN only. In `run.sh`, judge the version of Hadoop MapReduce running, and use EXAMPLE or JOBCLIENT