In original design, payment method response data is passed between processes
through a simple nsString. It means a special encoder/decoder is needed for
special response data, ex. BasicCardResponse, to serialize/deserialize
into/from the nsString. However, when a token spliter, ':', ';' and '@', is
used in response data, it makes the encoder/decoder can not work normally.
It is hard to define a suitable token spliter set for encoder/decoder.
So instead of using an error-prone encoder/decoder, this patch defining a new
IPC structure for response data.
e90829472b