Bump example config to latest CM 4.7.2
Implement JDK install role, paramaterise with optional JDK install URL
Ensure yum excludes are observed
Reinstate retry yum installs with valid exclude clause
Add JDK installed config paramater, ensure working dir is returned to after JDK installed
Make all wget's quiet
Make unzip quiet
Merge pull request #46 from ggear/graham-patch-CDH-14822

CDH-14822: Whirr-CM to allow declarative, optionally externally hosted JDK provision