Fix summarize for old pandas versions
Fix summarize for old pandas versions

JDReutt/BayesDB,JDReutt/BayesDB,poppingtonic/BayesDB,JDReutt/BayesDB,poppingtonic/BayesDB,JDReutt/BayesDB,poppingtonic/BayesDB,poppingtonic/BayesDB,JDReutt/BayesDB,poppingtonic/BayesDB