CDK-604: Added commands to generate logging and Flume configs

* The Flume configuration defaults to an AvroSource listening on 0.0.0.0:41415
* The Flume configuration defaults to a file channel
* The log4j configuration defaults to writing to port 41415, but requires the hostname
* The log4j configuration requires a package or class name to log to Flume, or a
  switch of --log-all to configure the rootLogger.
* Besides the unit tests, I ran some manual tests on a cluster by completing the
  logging example, but using the tool derived configs rather than the ones that
  shipped with the example.
I think it depends on whether the defaults are for demonstration purposes to just get it working or if we are trying to make these fairly well chosen defaults. I think we can't do the latter very well so we should make the defaults demo-focused. But where we can show best practice we should, like using the file channel by default. It sounds like putting these in the same directory would be misleading, so we should not combine them into a working directory option.

We can also add comments that explain what the options should be used for like configuration files in /etc typically do. At least for those that are defaulted. I think this would be a better thing to do than having options for these settings. We expect people to go back and edit the configuration once we output it, so we can simply add a comment block for the file channel that explains what the settings are in more detail and refers users to information on how to set them.