Fair Metadata

[EvanDietzMorris]

This is a fairly major rework of the metadata outputs for graphs

• implemented new outputs graph-metadata and schema (json-ld & schema.org)
• update knowledge source provenance metadata files to be more conformant to schema.org
• include more information about upstream knowledge sources for aggregator knowledge sources
• no longer include subgraph information or nesting in distributable metadata outputs, just flatten to one sources list
• still produce old metadata format as well for backward compatibility