MAHOUT-1541, MAHOUT-1568, MAHOUT-1569 fixed a build test problem, drivers have an option new to not search for MAHOUT_HOME and SPARK_HOME
Merge branch 'master' of https://git-wip-us.apache.org/repos/asf/mahout
MAHOUT-1541 backed out compatability with legacy Item Similarity, now outputs raw LLR scores
MAHOUT-1541, MAHOUT-1568, added option to ItemSimilarityDriver to allow output that is directly search engine indexable, also some default schema's for input and output of TDF tuples and DRMs
adding a two input option
Yikes, the cross-cooccurrence stuff is in the wrong order--a bug change so commit before making it