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.
The name is completely arbitrary, so users never have to care about this setting. Unless we're going to expand the command to let you specify other sources, this will always be used to send Avro events to the `DatasetSink`, so I'd be more inclined to use `avro-event-channel` and change the default source name to `avro-event-source`.