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, and demo examples have
    been updated accordingly.
 * This patch also includes some fixes needed to work on the CDH5.1
    QuickStart VM. I suspect more of the examples may have issues.
    So I'll file a follow-up JIRA to check them out and to update the
    top-level README to account for changes between the 4.4 and 5.1 VMs.
You could run off cluster in one of two ways:

1) Alias quickstart.cloudera to 127.0.0.1
2) Download the config directories for Hadoop and Hive and set HADOOP_CONF_DIR and HIVE_CONF_DIR

The first one is easy enough to do. We already had to have the user add localhost.localdomain for the old instructions because some macs and linux distros didn't have that by default.

The second one is a harder. It's not too bad if you have CM installed, but the QuickStart doesn't have it enabled by default.