Merge remote-tracking branch 'origin/v0.2' into zjw
add  schema /table /nodegroup service and DDL definition
add MetaUtil
modify geolocation
Add filterTableFiles and listTableFiles ObjectStore implementation, but not tested yet
Merge remote-tracking branch 'origin/zhuqihan' into caoruyi
modify the geolocation
modify bug
Remove DataCenter related entries from DDL to JDO; Change DC handling to DB; Metastore reworked.
Remove invalid entries from DummyRawStoreForJdoConnection.java
Merge zjw's branch: add nodegroup related fixs.
Merge remote-tracking branch 'origin/zjw' into v0.2, add missing files.
rpc
Merge caoruyi's branch: geoloc
Merge zhuqihan's branch: DDL .g modification.
add showNodeAssignment
cmt agian
Merge remote-tracking branch 'origin/v0.2' into zhuqihan
modify SemanticAnalyzerFactory