Implementing the recordMetadata JSON from Schema v1.0 with small additions for v1.0.1.

This can be used like the commonProporties JSON in addition to the category specific JSONs. Please have a look if this is a good implementation of the PDF Schema. It's the first JSON Schema I write.

Like proposed in #36 (closed) and #23 (closed) it adds the new proporties "resourceCategory" and "schemaVersion". Other than proposed in #36 (closed) I did not add a new property "mappedByHub" as this would be only of short term value anyway and I propose to use the "creatorId" field for this short-term purpose for now, and later update it with more specific "creatorId"s or "updaterId"s. Any thoughts on this approch are appriciated.