Merge branch 'index_support' of https://git-wip-us.apache.org/repos/asf/tajo into TAJO-838_3
TAJO-1178: Some error messages for wrong JSON queries are not so much helpful. (Jaewoong Jung via jihoon)
TAJO-1195: Remove unused CachedDNSResolver Class. (DaeMyung Kang via jaehwa)

Closes #253
TAJO-1197: Unit test failed: unable to create new native thread. (jinho)

Closes #255
Merge branch 'master' of https://git-wip-us.apache.org/repos/asf/tajo into index_support
Merge branch 'index_support' of https://git-wip-us.apache.org/repos/asf/tajo into index_support
Merge branch 'TAJO-838_3' of github.com:jihoonson/tajo-2 into TAJO-838_3
Merge branch 'index_support' of https://git-wip-us.apache.org/repos/asf/tajo into TAJO-838_3