remove fallback to N/A for address zip_code and state
Merge pull request #105 from mthornhill/removezipcode

remove fallback to N/A for address zip_code and state
ensure that our addresses get deep copied when creating an order, need to set id and pk to None when copying an inherited model https://docs.djangoproject.com/en/1.4/topics/db/queries/#copying-model-instances
Merge pull request #106 from mthornhill/deepcopyaddresses

ensure that our addresses get deep copied when creating an order