Define resolution results as JSON, not JSON-LD.

[peacekeeper]

Addresses https://github.com/w3c/did-resolution/issues/137

[peacekeeper]

Note that this also removes the current DID Resolution JSON-LD context file: https://w3c.github.io/did-resolution/contexts/did-resolution-v1.json

[ottomorac]

WG Discussion on 22-May:

markus_sabadello: there is consensus in using plain JSON, rather than JSON-LD for DID resolution. PR seeks to address that change

JoeAndrieu: did we talk earlier about Ivan do work that would potentially be unnecessary if we adopt this position. Worth clarifying

ivan: Not related. As we are discussing whether there should a JSON-LD dialect for DID Resoltuion. Ivan did not touch this. He worked on the DID spec vocabulary

[peacekeeper]

No objections, multiple approvals, merging.