test alterschema
Upgrade datanucleus to new version and eliminate using SchemaTool create oracle sql script; Implement truncTableFiles to drop all files in one table; Fix drop table and drop index; Do re-authentication on reconnect.
Merge remote-tracking branch 'origin/zhuqihan' into v0.2, OK
Fix Entity fix for tables. Worked?
Merge caoruyi's branch and fix ql.* import in HiveMetaStoreClient.