HIVE-9036: Replace akka for remote spark client RPC [Spark Branch] (Marcelo via Xuefu)

git-svn-id: https://svn.apache.org/repos/asf/hive/branches/spark@1644322 13f79535-47bb-0310-9956-ffa450edef68
HIVE-9042: Support multiple mapjoin operators in one work [Spark Branch] (Jimmy via Xuefu)

git-svn-id: https://svn.apache.org/repos/asf/hive/branches/spark@1644328 13f79535-47bb-0310-9956-ffa450edef68
Merge remote-tracking branch 'upstream/spark' into spark