barstock "n.d." dates

[evanwill]

@kxuidaho @aweymo-ui new items added to barstock contain "n.d." as a date value. The "date" field should only contain ISO dates, no other text (i.e. "n.d." = blank). Please clean up these dates! If necessary create an "archival_date" field to hold the information.

[aweymo-ui]

I didn't find any time spans in the date range so I turned the n.d. to blanks, updated the csv and redeployed.