YARN-679: javadocs and import cleanup
YARN-679 remove spurious override in NonExitingServiceLauncher of getter
YARN-679 make some of the getters in ServiceLauncher final -these aren't things classes should be overriding (they can still override the setters...)
YARN-679 ServiceLauncher uses reflection to try to create HdfsConfiguration and YarnConfiguration -this list is extensible. It is not an error if they cannot be created -only logged at debug
YARN-679  YarnServiceLauncher subclass always creates a YarnConfiguration for the service to launch off
YARN-679  remove YarnServiceLauncher as it should not be needed
YARN-679  update package-info doc with latest state of config loading
YARN-679 adopt GenericOptionsParser with reworks to tests -including scan for valid conf filenames