Persist OriginalRecord

This is a substantial rewrite of OriginalRecord to allow them to persist to LDP.

This isn't mergeable until the forthcoming Marmotta `3.3.0` release and a corresponding update to `marmottawrapper`.  Until then, I submit it for sanity check.
This satisfies Rubocop, and the YARD documentation (esp. w/ addition of `@abstract`) provides good documentation for how this is to be implemented.