Use JSON-LD to model descriptors

[cadorn]

Use http://json-ld.org/ to model the pinf-it normalized descriptors:

• e.g. https://github.com/pinf-it/pinf-it-package-insight/blob/master/test/assets/descriptors/npm/q.package.insight.json#L84
• e.g. https://github.com/pinf-it/pinf-it-program-insight/blob/master/test/assets/descriptors/boot-package.program.insight.json#L14

cc @kriskowal I am going to try and use JSON-LD to hold configs in the virtual system and write converters to and from this format. It should be trivial to integrate the JSON-LD model into the layered filesystem and feed properties on the prototype chain of an object. I am going to explore some minimal extensions to JSON-LD + JSON-SCHEMA that will add support for mapping to JS code bundles that can be executed when processing schemas or when data passes through it ... This will be the foundation of the meta system that maps in every aspect used within a given context and can attach tooling components to API responses.

[cadorn]

JSON-LD intro video & docs: https://github.com/digitalbazaar/jsonld.js/issues/96#issuecomment-82366048