TAJO-886: Add IRC page to community section in site.

Closes #45
TAJO-882: CLI hangs when a error occurs in the GlobalPlanner. (Hyoungjun Kim via hyunsik)

Closes #42
TAJO-887: Eliminate HiveQL support feature.

Closes #46
TAJO-887: Eliminate HiveQL support feature. (missed elimination of hiveql config).
TAJO-890: Redirect stdout of maven test to /dev/null in Travis CI script.

Closes #47
TAJO-866: COUNT DISTINCT with other aggregation function throws ClassCastException. (Hyoungjun Kim via hyunsik)

Closes #36
TAJO-874: Sometimes InvalidOperationException occurs when aggregates TableStat. (Hyoungjun Kim via hyunsik)
TAJO-874: Sometimes InvalidOperationException occurs when aggregates TableStat. (Hyoungjun Kim via hyunsik)

Closes #38
Merge branch 'master' of https://git-wip-us.apache.org/repos/asf/tajo into TAJO-884