Come up wih a design for how we can track multiple entires of 'Inventory Fulfilled' events.

[mgurley]

Add a 'Partially Fulfilled' Specimen status and allow it to be saved multiple times. Decide whether to place the fulfillment details on the 'disburser_request_statuses' table (easier but hacky) or a new table disburser_request_specimen_fulfillments that is the child of disburser_request_statuses (harder but less hacky).