Cleanup save_species and misc enhancements

This commit does a number of things:
* Modernizes the save_species function to match changes to business logic
* Moves the dict_to_model workflow out of each individual processing fn
* Makes model processing more DRY
* Makes model processing safer by passing each model through schema validation
* Makes model processing more powerful by allowing early exists
* Renames vars to be more semantic
* Fixes priority ordering to force tree before audit
Don't migrate deleted OTM1 objects