Fix: string columns with dates failed to render.
Fix: string columns with dates failed to render.

jmvasquez/redashtest,vishesh92/redash,useabode/redash,easytaxibr/redash,jmvasquez/redashtest,pubnative/redash,imsally/redash,moritz9/redash,imsally/redash,guaguadev/redash,pubnative/redash,pubnative/redash,amino-data/redash,ninneko/redash,rockwotj/redash,jmvasquez/redashtest,vishesh92/redash,stefanseifert/redash,guaguadev/redash,moritz9/redash,ninneko/redash,M32Media/redash,akariv/redash,44px/redash,stefanseifert/redash,ninneko/redash,easytaxibr/redash,rockwotj/redash,moritz9/redash,alexanderlz/redash,alexanderlz/redash,crowdworks/redash,rockwotj/redash,pubnative/redash,EverlyWell/redash,akariv/redash,getredash/redash,hudl/redash,crowdworks/redash,EverlyWell/redash,ninneko/redash,crowdworks/redash,44px/redash,stefanseifert/redash,guaguadev/redash,denisov-vlad/redash,guaguadev/redash,guaguadev/redash,useabode/redash,easytaxibr/redash,44px/redash,hudl/redash,M32Media/redash,chriszs/redash,alexanderlz/redash,denisov-vlad/redash,denisov-vlad/redash,getredash/redash,akariv/redash,vishesh92/redash,stefanseifert/redash,useabode/redash,ninneko/redash,jmvasquez/redashtest,M32Media/redash,M32Media/redash,amino-data/redash,useabode/redash,getredash/redash,amino-data/redash,crowdworks/redash,denisov-vlad/redash,44px/redash,EverlyWell/redash,rockwotj/redash,pubnative/redash,akariv/redash,akariv/redash,moritz9/redash,chriszs/redash,alexanderlz/redash,chriszs/redash,EverlyWell/redash,hudl/redash,denisov-vlad/redash,jmvasquez/redashtest,easytaxibr/redash,chriszs/redash,amino-data/redash,imsally/redash,getredash/redash,easytaxibr/redash,hudl/redash,getredash/redash,imsally/redash,vishesh92/redash,stefanseifert/redash