SPARK-1209 [CORE] (Take 2) SparkHadoop{MapRed,MapReduce}Util should not use package org.apache.hadoop

andrewor14 Another try at SPARK-1209, to address https://github.com/apache/spark/pull/2814#issuecomment-61197619

I successfully tested with `mvn -Dhadoop.version=1.0.4 -DskipTests clean package; mvn -Dhadoop.version=1.0.4 test` I assume that is what failed Jenkins last time. I also tried `-Dhadoop.version1.2.1` and `-Phadoop-2.4 -Pyarn -Phive` for more coverage.

So this is why the class was put in `org.apache.hadoop` to begin with, I assume. One option is to leave this as-is for now and move it only when Hadoop 1.0.x support goes away.

This is the other option, which adds a call to force the constructor to be public at run-time. It's probably less surprising than putting Spark code in `org.apache.hadoop`, but, does involve reflection. A `SecurityManager` might forbid this, but it would forbid a lot of stuff Spark does. This would also only affect Hadoop 1.0.x it seems.

Author: Sean Owen <sowen@cloudera.com>

Closes #3048 from srowen/SPARK-1209 and squashes the following commits:

0d48f4b [Sean Owen] For Hadoop 1.0.x, make certain constructors public, which were public in later versions
466e179 [Sean Owen] Disable MIMA warnings resulting from moving the class -- this was also part of the PairRDDFunctions type hierarchy though?
eb61820 [Sean Owen] Move SparkHadoopMapRedUtil / SparkHadoopMapReduceUtil from org.apache.hadoop to org.apache.spark
SPARK-3179. Add task OutputMetrics.

Author: Sandy Ryza <sandy@cloudera.com>

This patch had conflicts when merged, resolved by
Committer: Kay Ousterhout <kayousterhout@gmail.com>

Closes #2968 from sryza/sandy-spark-3179 and squashes the following commits:

dce4784 [Sandy Ryza] More review feedback
8d350d1 [Sandy Ryza] Fix test against Hadoop 2.5+
e7c74d0 [Sandy Ryza] More review feedback
6cff9c4 [Sandy Ryza] Review feedback
fb2dde0 [Sandy Ryza] SPARK-3179