ADD FREEBIES
* fill up all fields and click add button to add freebies
* to edit freebie qty select the same freebie on the dropdown and input the updated qty
* to remove freebie, select the same freebie on the dropdown and input 0 on qty
* to edit freebie qty select the same freebie on the dropdown and input the updated qty
* to remove freebie, select the same freebie on the dropdown and input 0 on qty