HIVE-4658 : Make KW_OUTER optional in outer joins (Edward Capriolo via Navis)

git-svn-id: https://svn.apache.org/repos/asf/hive/trunk@1502758 13f79535-47bb-0310-9956-ffa450edef68
Merge remote branch 'origin/trunk' into trunk-gd
Merge remote branch 'origin/trunk-gd' into fb-HIVE-4791-trunk-gd