Remove calls to deprecated mapred's OutputCommitter.cleanupJob

Since Hadoop 1.0.4 the mapred OutputCommitter.commitJob should do cleanup job via call to OutputCommitter.cleanupJob,

Remove SparkHadoopWriter.cleanup since it is used only by PairRDDFunctions.

In fact the implementation of mapred OutputCommitter.commitJob looks like this:

  public void commitJob(JobContext jobContext) throws IOException {
    cleanupJob(jobContext);
  }