MAHOUT-1500 H20 

Creating a PR to just to be able to (re-)view what current state of diff is against master in this work.
Well one fundamental thing that i surely missed is that this module's physical operators are written in java wheres all tests and apis are in scala. So the maven module is fragmented between java and scala code. Something i was intentionally tried to avoid (either module is 100% java, or 100% scala).

I suppose it is not going to stop it from committing now, but it just shows how superficial my initial review was.