TAJO-1038: Remove use of Builder variable in Schema.

Closes #140
TAJO-1034: Reduce Explicit Use of JVM Internal Class. (Jihun Kang via hyunsik)
TAJO-1024: RpcConnectionPool::getConnection can cause NPE at initialization.

Closes #139
TAJO-1037: KillQuery hang in subquery init state. (jinho)

Closes #137
TAJO-1015: Add executionblock event in worker. (jinho)

Closes #124
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
TAJO-1054: Wrong comment in ByteUtils.splitWorker(). (Jongyoung Park via jinho)
TAJO-1046: Remove hadoop native dependency of pullserver. (jinho)

Closes #143
TAJO-1016: Refactor worker rpc information. (jinho)

Closes #125
TAJO-1050: RPC client does not retry during connecting. (Jihun Kang via jinho)
TAJO-1056: Wrong resource release or wrong task scheduling. (jinho)

Closes #151
TAJO-1047: DefaultTaskScheduler:allocateRackTask is failed occasionally on JDK 1.7. (jinho)

Closes #144
TAJO-1049: Remove the parallel degree limit up to the maximum cluster capacity.

Closes #147
TAJO-1035: Add default TAJO_PULLSERVER_HEAPSIZE

Closes #148
TAJO-910: Simple query (non-forwarded query) should be supported against partition tables.

Closes #138
TAJO-667: Add math function documentation. (Jongyoung Park via hyunsik)

Closes #153
Merge branch 'master' of https://git-wip-us.apache.org/repos/asf/tajo