Allow custom values to determine the status of a location and merging some information into "additional_info" for viz purposes

[Zebreu]

We expect 0 and 1 for the closed field currently, as part of the custom_headers.yml, and we'd like to allow a customer to set which value will filter out locations to visit. Additionally, if some of the columns have interesting data, we'd like to allow a customer to show the data from other columns on the map via the additional_info field, concatenated perhaps.