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
TAJO-1259: A title in catalog configuration document is different from others. (Jongyoung Park via hyunsik)

Closes #310
TAJO-1261: Separate query and ddl execution codes from GlobalEngine.

Closes #312
TAJO-1250: RawFileAppender occasionally causes BufferOverflowException. (jinho)

Closes #303
TAJO-1262: Rename the prefix 'SubQuery' to 'Stage'.

Closes #314
TAJO-1259: Change tsql history behavior. (Jaewoong Jung via hyunsik)

Closes #316
TAJO-1249: Tajo should check if a file format given in DDL is supported. (DaeMyung Kang via hyunsik)

Closes #313
TAJO-1268: tajo-client module should not use UserGroupInformation.

Closes #318
TAJO-1267: Remove LazyTaskScheduler. (DaeMyung Kang via jihoon)
TAJO-1266: Too many logs when writing a parquet relation. (DaeMyung Kang via jihoon)

Closes #320