TAJO-1172: Remove Trevni storage type and its related classes (DaeMyung Kang via hyunsik)

Closes #244
TAJO-1184: Upgrade netty-buffer to 4.0.24.Final. (jinho)

Closes #248
TAJO-1178: Some error messages for wrong JSON queries are not so much helpful. (Jaewoong Jung via jihoon)
Merge branch 'master' of https://git-wip-us.apache.org/repos/asf/tajo into TAJO-1033

Conflicts:
	tajo-storage/src/main/resources/storage-default.xml
	tajo-storage/src/test/resources/storage-default.xml