Changes since first patch:
1. make the kafka csv metrics reporter a singleton — only one instance in one JVM
2. adding csv metrics reporter support for producer / consumer /producer-performance / console-consumer
3. fix a few places in the system test to make it actually working — with producer_performance and console-consumer, and plotting graph correctly
4. there's only one problem left : some of the metrics are of type "time", according to the doc, timer reports data as both a Meter and Histagram. (this is also verified in the JMX console)
But for the exported CSV file, we only see the header like:
That's to say, we cannot find the Meter / rate related metrics.
For a fiew graphs requiring "One minute rate" from a timer metric (and only for them), the data are not reported and graphs are not plotted