The .stats.csv and .important_sub_metrics.csv extensions may not be permanent. We might have to change it in future. So, we need to figure out a way for reporting to ask each metric for the stats and important_sub_metric file name directly. 

Can we implement some reporting functionality in the metric class themselves? If not, may be expose a method in metric classes to do that. 

Basically, lets try to write these different modules (metric modules, graphing modules, reporting modules) such a way that making a change in one module does not need updating other modules.... :)