MAHOUT-1615: drmFromHDFS returning the same Key for all Key,Vec Pairs for Text-Keyed SequenceFiles

SparkContext.sequenceFile(...) will yield the same key per partition for Text-Keyed Sequence files if the key a new copy of the key is not created when mapping to an RDD.  This patch checks for Text Keys and creates a copy of each Key if necessary.    
we want of course to fix it. unfortunately i am still unable to compile h20. I read somewhere that the error i am getting means there's a broken jar in classpath, but i am still getting this error even after i cleaned out my entire local maven repo.