add showNodeAssignment
cmt agian
Merge remote-tracking branch 'origin/v0.2' into zhuqihan
modify SemanticAnalyzerFactory
merge with zjw
modify hive.g about nodeAssignment
Merge remote-tracking branch 'origin/zjw' into zhuqihan
remerge with zjw to solve hive.g mistake
add/drop/modify/show nodeGroup
merge zhuqihan