XD-2107&1048: --nameExpression for metrics & --incrementExpression for agg-counter

Previously we knew the counter name right off the bat, now we don't. Previously, we created the counter (knowing the name) with its alpha value and re-used that alpha value when a counter increment arrived. We can't to this anymore.

I was not happy with that change myself, but came to realize that using the alpha value (with arguably a different value each time) is not that crazy after reading http://www.amazon.fr/Doing-Data-Science-Rachel-Schutt/dp/1449358659/ref=sr_1_1?ie=UTF8&qid=1413299159&sr=8-1&keywords=doing+data+science