Only allow dataset table download if data is in datahub (#451)
Only allow dataset table download if data is in datahub (#451)

* Download icon no longer shows if the study is not on datahub.


Former-commit-id: 015562c7960b8ba4924eda6319deab50ddfe9664
alisman/cbioportal-frontend,cBioPortal/cbioportal-frontend,cBioPortal/cbioportal-frontend,alisman/cbioportal-frontend,cBioPortal/cbioportal-frontend,alisman/cbioportal-frontend,cBioPortal/cbioportal-frontend,alisman/cbioportal-frontend,alisman/cbioportal-frontend,cBioPortal/cbioportal-frontend,cBioPortal/cbioportal-frontend,alisman/cbioportal-frontend