TAJO-21: CREATE EXTERNAL TABLE should support a file path (JaeHwa Jung)
TAJO-32: Cleanup TaskRunner. (hyunsik)
TAJO-33: Implement a basic query progress indicator. (hyunsik)
TAJO-38 Update class comment in TaskAttemptContext from Korean to English
TAJO-38 Update CHANGES.txt file.
TAJO-42: Divide SubQuery into FSM and execution block parts. (hyunsik)
TAJO-44: Adopt AMRMClient to RMContainerAllocator, RMCommunicator. (hyunsik)
TAJO-47: RowFile has the duplicated initialization problem and unflipped ByteBuffer problem. (jihoon)
update doc to change Yarn home env from YARN_HOME to HADOOP_YARN_HOME.
TAJO-50: Cleanup SubQuery. (hyunsik)
TAJO-37: Remove obsolete classes WorkerEventDispatcher, WorkerEvent and WorkerEventType. (sunny.1324 via hyunsik)