add china_city gem.
init china_city.
add convenient css method: margin-right.
add event order shipping address model.
save order address in model and controller.
save order address.
fixed rspec error.
merge master.
validate shipping address at server.
database_cleaner 1.1.1 has a bug when using sqlite
Merge pull request #517 from jasl/back-database-cleaner

修复使用sqlite3时database_cleaner错误的使用pg_adapter而异常
validate order quantity and address on create.
Merge pull request #511 from saberma/saberma-feature/463-save-order-shipping-address

用户可以录入发票收货地址等信息 #463