TAJO-873: Query status is still RUNNING after session expired. (Hyoungjun Kim, jinho)

Closes #37
TAJO-906: Runtime code generation for evaluating expression trees.

Closes #113
Merge branch 'master' of https://git-wip-us.apache.org/repos/asf/tajo into TAJO-1015

Conflicts:
	tajo-core/src/main/java/org/apache/tajo/worker/TajoResourceAllocator.java
	tajo-core/src/main/java/org/apache/tajo/worker/TajoWorker.java
	tajo-core/src/main/java/org/apache/tajo/worker/TajoWorkerManagerService.java
	tajo-core/src/main/java/org/apache/tajo/worker/Task.java
fixed unit test failure