MAHOUT-1262 Cleanup LDA code

git-svn-id: https://svn.apache.org/repos/asf/mahout/trunk@1493648 13f79535-47bb-0310-9956-ffa450edef68
MAHOUT-1264 Performance optimizations in RecommenderJob

git-svn-id: https://svn.apache.org/repos/asf/mahout/trunk@1493660 13f79535-47bb-0310-9956-ffa450edef68