Add Hochschulkompass classification

[acka47]

I added a commit (2235c1e) although you might prefer automating using topConceptOf instead of inScheme for the top concept.s

The result looks already really good and I am ok with merging and iterating over the result.

After taking a look at it and running qSKOS over the vocab, here are two necessary improvements (I added an nice-to-have at https://github.com/hbz/skohub-ssg/issues/1#issuecomment-493882836):

• We should already use a "real" namespace under http://w3id.org/class/hrk or so. we have to think about a proper name/acronym.
• Overlapping labels: there are 28 labels that are used for two separate concepts

[literarymachine]

Discussed @acka47 to use slash URIs, see https://github.com/hbz/skohub-pubsub/issues/7#issuecomment-473870729