TAJO-224: Rearrange DataType enumeration and Refactor type systems. (hyunsik)
TAJO-199: All relations in catalog must have data volume size. (hyunsik)
TAJO-223: Maximize disk read bandwidth utilization of StorageManagerV2 by moving Tuple creation role to next() (Keuntae Park via hyunsik)
TAJO-220: Implement catalog dump feature. (hyunsik)
TAJO-229: Implement JoinGraph to represent a graph of relation joins. (hyunsik)
TAJO-226: Can't use group by column alias. (hyunsik)
TAJO-148: Implement UPPER(text), LOWER(text) function. (hyunsik)
TAJO-147: Implement trim(text), ltrim(text), and rtrim(text) function. (hyunsik)
TAJO-179: Support MySQL CatalogStore. (jinho)
TAJO-179: Support MySQL CatalogStore. (removed useless code)
TAJO-232: Rename join operators and add other join operators to PhysicalPlanner. (hyunsik)
Merge branch 'master' of https://git-wip-us.apache.org/repos/asf/incubator-tajo into TAJO-99

Conflicts:
	tajo-core/tajo-core-backend/src/main/java/org/apache/tajo/engine/planner/graph/DirectedGraph.java
	tajo-core/tajo-core-backend/src/main/java/org/apache/tajo/engine/planner/graph/Graph.java
	tajo-core/tajo-core-backend/src/main/java/org/apache/tajo/engine/planner/graph/SimpleDirectedGraph.java
	tajo-core/tajo-core-backend/src/main/java/org/apache/tajo/engine/planner/graph/SimpleUndirectedGraph.java
Add join order builder.