Permalinks programmes. Fix for #37

For the 8th October Datasprint, a temporary solution to address the lack of permalinks/URIs for some programmes. These programmes are now modelled as BNode. This does not change anything to existing programmes, but this merge shouldn't be necessary once this is fixed on the db side.

Closes #37 (closed)

Update 2020-10-27

Integrate this in v1.0 of the code. All permalinks of programmes on the Cinema Context website are ending up in the data this way.