To bundle or not to bundle our Schemas

@lucas.kulla and I agreed, that at shorthand, for easier implementation into software, we would like to put the Record Metadata in the same file as the CommonProperties as an embedded sub-schema.

In-midterm we should rather make use of the new Bundling capabilities of the latest JSON Schema Standard which we would still need to adopt. This will make Schema development clearer.

see also #48 and #47