Merge pull request #19 from abayer/master

Fix Impala parcel URL for GA
Do not invoke prepare_all_disks when overiden by whirr.cm.data.dirs.root, ensure data directories are created in any case
Update Hive service wide config with zookeper service link, dropping safety valve settings, new feature of CM 4.5.2
If CM license provided, ensure services have correct instrumentation settings applied
Merge pull request #20 from ggear/graham-patch-CDH-11869

Graham patch for CDH-11869
Add Impala repos for package installation