TAJO-122: Add EXPLAIN clause to show a logical plan. (DaeMyung Kang via hyunsik)
TAJO-502: Jenkins build is failing. (jinho)
Improved union.
Fixed almost bugs.
Merge branch 'master' of https://git-wip-us.apache.org/repos/asf/incubator-tajo into LogicalPlanRefactor
TAJO-503: HCatalogStore can't scan several hive databases. (jaehwa)
TAJO-166: Automatic precommit test using Jenkins. (hyunsik)
TAJO-457: Update committer list and contributor list. (hyunsik)
Merge branch 'master' of https://git-wip-us.apache.org/repos/asf/incubator-tajo into LogicalPlanRefactor