TAJO-1246: HBase info port conflict occasionally causes unit test failures in Jenkins CI.

Closes #300
TAJO-1252: PathValidator should allow hdfs paths which contain IP addresses. (jihoon)
TAJO-1221: HA TajoClient should not connect TajoMaster at the first. (jaehwa)

Closes #286
TAJO-1254: Fix getProgress race conditions in Query. (jinho)

Closes #304
TAJO-324: Rename the prefix 'QueryUnit' to Task.

Closes #306
TAJO-1232: Implicit groupby queries with LIMIT lead to wrong results. (jihoon)
TAJO-1247: Store type 'TEXTFILE' should be TEXT while keeping enum 'TEXTFILE' in protobuf. (DaeMyung Kang via hyunsik)

Closes #302
Merge remote-tracking branch 'upstream/master' into TAJO-527
TAJO-527: Upgrade to Netty 4