TAJO-1111: TestKillQuery.testKillQueryFromInitState occasionally fails.

Closes #198
TAJO-1113: SubQuery in KILLED state should handle unexpected events.

Closes #199
[maven-release-plugin] prepare release release-0.9.0-rc0
[maven-release-plugin] prepare for next development iteration
Merge branch 'master' of https://git-wip-us.apache.org/repos/asf/tajo into index_support
Change the pom version of tajo-hcatalog to 0.9.1-SNAPSHOT.
Merge branch 'master' of http://git-wip-us.apache.org/repos/asf/tajo into TAJO-838_2
Merge branch 'master' of http://git-wip-us.apache.org/repos/asf/tajo into index_support
Merge branch 'index_support' of http://git-wip-us.apache.org/repos/asf/tajo into index_support
Merge branch 'index_support' of http://git-wip-us.apache.org/repos/asf/tajo into TAJO-838_2