HIVE-7584 - Change SparkCompiler to generate a SparkWork that contains UnionWork from logical operator tree (Na Yang via Brock) [Spark Branch]

git-svn-id: https://svn.apache.org/repos/asf/hive/branches/spark@1616652 13f79535-47bb-0310-9956-ffa450edef68
HIVE-7560 - StarterProject: Fix exception handling in POC code (Chao Sun via Brock) [Spark Branch]

git-svn-id: https://svn.apache.org/repos/asf/hive/branches/spark@1616653 13f79535-47bb-0310-9956-ffa450edef68
HIVE-7652 : Check OutputCollector after closing ExecMapper/ExecReducer (Venki Korukanti via Szehon) [Spark Branch]

git-svn-id: https://svn.apache.org/repos/asf/hive/branches/spark@1616663 13f79535-47bb-0310-9956-ffa450edef68