Flexible Validators (applying thresholding)

Overall the multiprocessing validator and singleprocess validator could take a ```List[Callable]``` and abstract out the verification process.

Any validation requires a file to be opened. This is strictly a pre-processing step before the files can be used for modeling.
Because of that it is possible to apply threshold values for fields within the open file to classify it as a ```validated_file``` or ```skip_file```

yet it is not yet clear to me how to structure this code.