Add JSON-LD to WebAPI

[mweidling]

Resources should follow the JSON-LD convention of assigning the resource URL as @id attribute.

Document JSON-LD convention for @id.

See #173.

[krvoigt]

@mweidling Is this also part of the reference implementation?

[mweidling]

No, we want to implement/add it to the API in general, but it's not essential. That's why we postponed it.

[kba]

No, we want to implement/add it to the API in general, but it's not essential. That's why we postponed it.

The Resource schema definition contains @id for the URL, that is in the draft already. And frankly, that is the only feature I really think is important for the Web API. I don't think we need full JSON-LD with @context and semantic mapping of property names etc. for such a limited and pragmatic API.