USER STORY: As a store owner, I would like to be able to add a brand to my store, so I can add new products even if the product's brand is not in the store yet

[JoyZadan]

Testing the adding of a product in the product management functionality, it was not possible to add a new product when it's brand is not yet in the store. The store owner need's to add the brand to using the Django admin first.

To fix this, and since the code to add a brand is pretty much similar to adding a product and the custom clearable file input can also be reused, it makes sense to add the brand management functionality, starting with adding a brand.