Modify materialize subclass inferences script to support versioning implementation

[rjyounes]

See #979

[rjyounes]

@dylan-sa I see two options here - you might have other ideas:

1. Simplest: don't include an ontology header in the subclass ontology
2. Move the ontology header triples out into a separate file, and read those into the output graph. That way the script can stay the same but be extended to other projects, where each one would have its own metadata file. In that case the script has to accept an argument indicating the location of the header file.

@coltonglasgow @Jamie-SA I'm thinking we can put this generalized Python script into the sub-module. Using option 1, that would be it. Using option 2, the script would be in the sub-module but each repo would store its own header triples.

[rjyounes]

Can't figure out what the issue is. Closing.