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.
Whenever I modify a mature file that someone else has created, my general rule is to stay with the style of the collective authors. Here I agree that the 1.0, 0.0 is better I'm hesitant to change it here when 1, and 0 are used throughout the file and I don't want to change it everywhere. There is probably more chance of me messing something up accidentally than actually fixing something if I change the whole file. If this seem wrong let me know but in past jobs we did this to avoid constant thrash over minor style disagreements.