Use ImageField for shop.ProductImage

- Use save function from Gallery for shop.ProductImage
- Change ImageField to FileField
- Remove redundant ImageField from ProductImageAdmin and CategoryAdmin
- Edit wishlist template to use File Object
Update Cartridge Fixtures and Manangement to use ImageField

- update image urls in fixtures
- move test images to static/media/uploads/product
- update copy_test_to_media()
Add migrations
Use modified version of mezzanine's .gitignore with cartridge