Fixes part of MAHOUT-1155.

https://issues.apache.org/jira/browse/MAHOUT-1155

Doesn't update Centroid because that is now part of the larger Vector changes
in https://issues.apache.org/jira/browse/MAHOUT-1202.



git-svn-id: https://svn.apache.org/repos/asf/mahout/trunk@1478836 13f79535-47bb-0310-9956-ffa450edef68