Add GND links

[acka47]

Some of the organisations in lobid also have a GND entry. We should add the GND URI with sameAs where it exists.

I already made some work on this which can be improved, though.

1. Getting all sub-terms of "Library" from the GND: https://github.com/hbz/lobid-organisations/wiki/GND-Schlagw%C3%B6rter-f%C3%BCr-bibliothekarische-Einrichtungen
2. Get a list of libraries (not terminated ones) within the GND (based on 1.): https://gist.github.com/acka47/312c81a453b89e908614b7c813967cd8
3. Run the list from 2.) against the lobid-organisations reconciliation endpoint.

I also did 3.) that but wasn't very satisfied with the result although I did a lot of manual matching in the end. This may due to my only partial knowledge of Open Refine...