Update hadoop scripts to support YARN

Updated hadoop cluster setup to use either MRv1 or MRv2 (YARN).  Scripts use YARN based if Hadoop executable version is >= 2.2, otherwise use MRv1.

Added a hadoop script (cb_run_kmeans.sh) that can be run manually on the SUT after CloudBench has created a hadoop AI.  This script creates the kmeans dataset and executes kmeans, then reports to CloudBench the kmeans database creation time, plus throughput data from the kmeans workload.

For vCloud Director, added enhancement to inject hostnames to be used inside VMs when vCloud Director instantiates them.  Previously, the hostname inside the VM was determined by the vCloud "vApp" definition. (Note that here I'm using the term "vApp" as it is used within vCloud Director, not as its used in CloudBench).  Explicitly naming VMs eliminates the need to have DNS running within vCloud.