Make relationships compatible with Laravel convention

Currently, some dropdown menus use relationships to tables that are defined in the model, and passed to the BREAD via Voyager. or example, the supplier field of table antibodies provide a dropdown of names entered in the suppliers table.

The issue is that the antibodies table stores the name of the supplier and not the supplier_id. This results from the fact that in v1.0.0 we used to store names and we had to be compatible for migrating to v2.0.0.

We should now fix this to have clean and safe database structure and models.