TAJO-1121: Remove the 'v2' storage package.

Closes #203
Merge branch 'master' of https://git-wip-us.apache.org/repos/asf/tajo into TAJO-1125

Conflicts:
	tajo-core/src/main/java/org/apache/tajo/engine/planner/PhysicalPlannerImpl.java
	tajo-core/src/main/java/org/apache/tajo/engine/planner/physical/HashShuffleFileWriteExec.java
	tajo-core/src/main/java/org/apache/tajo/engine/planner/physical/PartitionMergeScanExec.java
	tajo-core/src/main/java/org/apache/tajo/master/querymaster/Repartitioner.java
	tajo-core/src/main/java/org/apache/tajo/master/querymaster/SubQuery.java