Convert decomposer code to Hadoop 0.20 API

org.apache.mahout.math.hadoop classes (MatrixMultiplicationJob, TimesSquaredJob, TransposeJob) all use the deprecated Hadoop API. In the spirit of MAHOUT-167 and MAHOUT-143, I suggest converting them to Hadoop's 0.20 API.

The reason I'm raising this now is that this code no longer runs on my Hadoop 0.22-SNAPSHOT cluster (not sure why really - it was running fine about a month ago, but after updating to the latest Mahout trunk a few days ago the code throws "java.lang.RuntimeException: Error in configuring object" at MapTask.runOldMapper).

Also, the documentation at https://cwiki.apache.org/MAHOUT/dimensionalreduction.html is no longer accurate - the command line parameters have changed (even without the new arguments from MAHOUT-308). This is partly due to using the new argument parser which receives the input/output directories differently.