Enable Controlled Vocabularies

[billdenney]

Generate a set of data packages for https://evs.nci.nih.gov/ftp1/CDISC/SDTM/Archive/ and the related vocabularies at https://evs.nci.nih.gov/ftp1/CDISC/

[billdenney]

The preferred method will be to have a local cache of the remote data as described in https://stat.ethz.ch/pipermail/r-package-devel/2019q4/004780.html