Code review comment for lp:~roger-lp/ladon/trunk

I have decided to implement these two methods because I have faced with needs of interaction with request parameters which should be returned to client without changes (pass back parameters), it means that such parameters are used as markers, like "id" parameter in json-rpc requests and responses.

get_passback_params() is used for extracting "pass back parameters" from request parameters list.
add_passback_params() is used for putting, earlier extracted, "pass back parameters" into response parameters list.