TAJO-863: Column order mismatched in the JOIN query with asterisk selection. (Hyoungjun Kim via hyunsik)

Closes #31
TAJO-843: implements COALESCE for BOOLEAN, DATE, TIME, TIMESTAMP. (Hyoungjun Kim via hyunsik)

Closes #26
TAJO-860: Implements TRUNCATE table. (Hyoungjun Kim via hyunsik)
TAJO-860: Implements TRUNCATE table. (missed github closes)

Closes #29, #24.
TAJO-868: TestDateTimeFunctions unit test is occasionally failed.

Closes #34
TAJO-853: Refactoring FilterPushDown for OUTER JOIN
Resolved TAJO-870: FilterPushDown ignores a partitioned column in CASE expression within WHERE clause because TAJO-870 similar with TAJO-853
Merge branch 'master' of https://git-wip-us.apache.org/repos/asf/tajo into TAJO-853

Conflicts:
	tajo-core/src/test/java/org/apache/tajo/engine/query/TestJoinQuery.java