Define requirements for vocabularies

[KlausIllmayer]

We like to have a document where the requirements - in terms of technical and quality issues - of hosted vocabularies/concept schemes are defined. Based on this there should be also a definition of minimal information that we expect to find in the hosted vocabularies and concepts.

As not every vocabulary will support the requirements, there should be a kind of quality seal that expresses, how good a vocabulary implements the requirements (maybe like a traffic light: green is a full implementation, yellow a partly implementation and red does not comply with the requirements).

The requirements should be also published prominent on the vocabs service website.