Pull data from verbatim API to make use of degreeOfEstablishment and pathway

[peterdesmet]

The distribution API currently doesn't expose those terms, which is reported at gbif/checklistbank#294. It also seems that the status information is not always provided, which would filter out a lot of correct distributions from our unified checklist.

As a workaround, we should investigate if we can query the (uninterpreted) data from the verbatim API (e.g. https://api.gbif.org/v1/species/141117231/verbatim). This could also save on the number of requests that are being sent.

[PietrH]

https://gist.github.com/PietrH/82938952d47fd251366848ce3ec51c7d

[LienReyserhove]

See #94