HIVE-7709: Create SparkReporter [Spark Branch] (chengxiang via Xuefu)

git-svn-id: https://svn.apache.org/repos/asf/hive/branches/spark@1633382 13f79535-47bb-0310-9956-ffa450edef68
HIVE-8537: Update to use the stable TaskContext API [Spark Branch] (Chengxiang via Xuefu)

git-svn-id: https://svn.apache.org/repos/asf/hive/branches/spark@1633418 13f79535-47bb-0310-9956-ffa450edef68
HIVE-8540: HivePairFlatMapFunction.java missing license header [Spark Branch] (Chao via Xuefu)

git-svn-id: https://svn.apache.org/repos/asf/hive/branches/spark@1633473 13f79535-47bb-0310-9956-ffa450edef68
Merge remote-tracking branch 'upstream/spark' into spark