Support centralized metadata server

[eyadgaran]

currently db.initialize binds sqlalchemy objects in the session. leveraging #105 would split that into a standalone python package (can mix/match versions for orm vs core and library extensions) but fundamentally it still requires an in session reference.

updating the communication medium from persistable.orm_cls.save/etc to a standalone method that knows how to read env/config values to configure the payload and an over the wire call to the listening metadata server. tbd rest vs grpc

db.initialize can still be called in the same script but it implicitly starts a background server and updates the connection config to point at the corresponding localhost