fixed error deleting a product - caused because there are still invoice items referencing the product. Now, when a product is deleted, we just remove the reference to the invoice item, while retaining the invoice item for record keeping purposes.
API - The API has been overhauled and expanded. Originally the API was accessible via a single token. The new version is powered with web tokens which makes it a it more secure. The documentation for the API has also been updated to reflect these changes.
Beyond API infrastructure improvements, I've expanded all current API endpoints so the records can be created, updated, and deleted. In the previous version, records could only be shown, or listed.