MAHOUT-1561, MAHOUT-1568, MAHOUT-1569 text-delimited Spark readers and writers with drivers and a CLI for 'spark-itemsimilarity' closes apache/mahout#22
disabled ItemSimilarity test until we can work out how to run them without MAHOUT_HOME and SPARK_HOME being set
permanent fix for tests, now they do not require MAHOUT_HOME or SPARK_HOME
make the test --dontAddMahoutJars option hidden
fixed build test failure due to needing MAHOUT_HOME and SPARK_HOME, no longer required