requesting ACEi/ARBs and contrast to be added as additional categories for med_group

[jesstrynacode]

Would be helpful for my research interest to know if patients received ACEi/ARBs and/or contrast. See my suggestions posted in Common-Longitudinal-ICU-data-Format/CLIF#177.

[deetherese]

@jesstrynacode moved your comments to Common-Longitudinal-ICU-data-Format/CLIF#160