Do not assume a cart has its customer set.
Merge branch 'master' of http://github.com/visualspace/django-shopkit
Made using a Customer model optional, allowing for simpler Order models where customer management is not required.
Forgot one in last commit.
Made sure the ShippedOrderBase stuff doesn't assume a shipping_address as this makes no sense for simpler order models or when no automatic selection of methods is used.
Made ADDRESS_MODEL not required anymore.
Merge remote branch 'origin/cosmania' into sacksioni
Whitespace removal and reduced redundant query.
Merge remote branch 'origin/sacksioni'
Forgotten abstract = True, whitespace removal.
Updated CartAddBase view for updated cart API

Fix for #1 and whitespace removal.