MAHOUT-1604 Row Similarity 

This implements a driver for spark-rowsimilarity along with supporting code. This led to a refactoring of CooccurrenceAnalysis into SimilarityAnalysis since there are now two primary methods for item (column) similarity and row similarity.

Added read code to support reading extended DRM (text encoded with application specific ID) as well as one element per row encoding. Write still only supports extended  DRMs.

Changes relate to MAHOUT-1568 and MAHOUT-1569: Simplified creating a driver and parsing options.
No idea. I merge the master before any push. Your changes should be in with the merge, right? I could remove this and push it but would rather someone else do it so we can see if it happens again on my next merge.