Updating repo so that classes extend/implement those defined at bio4j main repository

Hey!

We just realized yesterday that we forgot at some point to adapt/update model classes here so that they implement or extends those defined at the main repository by means of the ones in the new and shiny blueprints-specific repository.

So far classes here have been extending those that were defined in the obsolete project BioinfoNeo4j - which were included temporarily in bioinfo-utils repo.

I'm going to create a new set of classes for all this here so that we have something equivalent to what we already got for the Titan implementation.

Let me know if you have any concern/insight on this :wink: 

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