MAHOUT-1464

The numNonZeroElementsPerColumn additions did not account for negative values, only counted the positive non-zero values. Fixed this in the in core and distributed case.

I added to Functions.java to create a Functions.notEqual. It may be possible to do this with the other functions but it wasn't obvious so I wrote one. The test is in MatrixOpsSuite, where is it used.

The distributed case was much simpler.

Changed tests to include negative values.
This is creating a Vector of non-zero counts per column, just like colSums is summing the column's values. The function is simply needed in the aggregateColumns. If you are suggesting another way to do this you'll have to be more explicit.

#17 has nothing to do with that afaict. It is about finding non-zero elements in a Vector.