Allow filtering by availability in the pizza product admin

Thom Wiggers
2018-03-14T13:09:35+01:00

### Short description

![Screenshot_from_2018-03-13_15-24-14](/uploads/33b288edc62d8da0a6b7a28d1130caa9/Screenshot_from_2018-03-13_15-24-14.png)