minor revisions to the README
with the code in place this extesion now works for redirecting the payment to Alipay payment gateway. (Tenpay not tested but should work too)
some minor teaks in spec code to reduce warnings
Refactored Alipay code to AlipayDecorator. This was intended to utilize the new ':prepend' (instead of :include) feature but it turned out that didn't work. It causes 'Stack level too deep' errors when the prepended method from the module calls 'super'
"acknowledge" of the "return" request was disabled. now enabled, and still working. :)
now Alipay code refactured.
  * code cleanup
  * creates logs entries
  * uses [order.number]_[payment.identifier] to identify payments sent to Alipay
log entries could be saved and displayed. TODO: need improve the entry content
added Chinese localization entries
Tenpay implementation done. this implementation separated the code handling "return" and "notification" requests into a dedicated "tenpay_status" controller, thus sheds some filter management code.
the Alipay code had a problem. It did not actually only respond to "update" requests using "alipay", but instead always acted as "alipay" was chosen. this problem was made obvious when "tenpay" was also implemented.
loading all ruby files intead of just the "_decorator" files when the rails engine is activated
Restructured code:
  * the redirect url is generated by code located in the alipay/tenpay respective decorators (to decorate checkout controller)
  * the postback (either the redirect back from alipay/tenpay, or the backend alipay server to our server notification) are processed by a new offsite_payment_status_controller
  * this offsite_payments_status_controller in turn uses a new service object (Spree::OffsitePayments::Processor, located in app/services/offsite_payments.rb) to hadle the business logic
  * changed routing to relect the above changes
  * added required i18n translations (Chinese version)
  * TODO: the code rendered obsolete by the above changes is _not yet_ removed
added Wxpay implementation. however, not fully working yet:
  * QRcode could be generated and displayed.
  * When user scans the QRcode and pays the bill in WeChat, the notification sent back from Wxpay server could be properly processed
  * and the order status could be successfully managed
  * other payment methods are still working
  * TODO: there is no AJAX call to poll the payment status. a manual click to a button has to be made to progress to order completion
  * TODO: when the order is paid, clicking the above said button leads to an empty cart page (it should lead to order completion page, but the current mechanism couldn't find the supposedly unpaid order).
setting branch for offsite_payments in Gemfile so the local repo could be used by bundler
bug fix regarding the types of "Spree::Payment.amount"