CDK-647: Update examples to use Flume's Log4jAppender and DatasetSink

* This patch includes configuring the Log4jAppender to gracefully
  handle connection errors. This is useful as it avoids a circular
  dependency between loading the log4j configuration to create the
  dataset and starting Flume after the dataset exists.
* The README for the logging, logging-webapp, demo, and json examples have
  been updated accordingly.
* This patch also includes some fixes needed to work on the CDH5.1
  QuickStart VM. CDK-656 has been filed to fix the other examples.
* The patch also updates logging and logging-webapp to use a Hive
  backed dataset. There is a configure-flume.sh script in the top-level
  to add the missing dependencies in CDH5.1. For 5.2, we should be able
  to remove that.
* The logging applications themselves no longer have any dependencies on Kite
  or HDFS! This means they can be used completely off the cluster! Once the
  examples are moved to use the CLI, I think it would be useful to have those
  examples NOT user the Kite parent pom to emphasise that any applicaiton
  can be connect to Hadoop with just log4j and the Flume Log4jAppender!

Closes #14