In get_validate_common, we first look in validate_data_store, then in the real data_store. This allows us the flexibility to use temp values for current workflow or real values set by previous workflows.
Also, lots of cleanup:
- we didn't use the dictionary returned by the set_data_common method, so removed it and only return the value we set.
- this allowed us to delete the `overwritten` method and some other code.
- renamed some variables to better represent what we are doing
