Add missing import

[yen3]

If I follow the instruction to add the url rule (url(r'^store/', include('stores.urls')),) and run test, the test would tell it does not know how include it is. Just import include function to resolve the problem.

[yen3]

好的，感謝你的回應

[uranusjr]

如果方便可以幫忙在這個 PR 改一下，我就可以直接 merge

[yen3]

你好，我試著修改，如果有問題再跟我說，謝謝。