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-978
TAJO-978: RoundFloat8 should return Float8Datum type.
Apply all jihoonson's comments(https://github.com/apache/tajo/pull/96#issuecomment-50293741).