TAJO-1040: Misuse netty HashedWheelTimer. (jinho)
TAJO-1048: Missed use of session variables in GlobalPlanner.

Closes #146
TAJO-948: 'INSERT INTO' statement to non existence table casuses NPE. (Jongyoung Park via hyunsik)

Closes #142
Merge pull request #1 from apache/master

Update master branch to my fork