TAJO-977: INSERT into a partitioned table as SELECT statement uses a wrong schema. (Hyoungjun Kim via hyunsik)

Closes #95
TAJO-974: Eliminate unexpected case condition in SubQuery. (Hyoungjun Kim via hyunsik)

Closes #974
TAJO-974: Eliminate unexpected case condition in SubQuery. (missed ticket close)

Closes #93
TAJO-952: Wrong default partition volume config. (Mai Hai Thanh via jihoon)
TAJO-980: execution page in Web UI broken.

Closes #97
TAJO-976: HashPartitioner doesn't make desired number of partitions infrequently. (Hyoungjun Kim via hyunsik)

Closes #94
TAJO-976: HashPartitioner doesn't make desired number of partitions infrequently. (Fixed a build failure due to 1.7 API)
Merge branch 'master' of https://git-wip-us.apache.org/repos/asf/tajo into TAJO-928

Conflicts:
	tajo-core/src/main/java/org/apache/tajo/master/querymaster/Repartitioner.java
Refactored QueryContext to take conf always.
Refactored TaskAttemptContext to not take TajoConf.