Adjust default UAS scenario to copy received RR to 200OK

[kadabusha]

RFC3261 states: When a UAS responds to a request with a response that establishes a dialog (such as a 2xx to INVITE), the UAS MUST copy all Record-Route header field values from the request into the response (including the URIs, URI parameters, and any Record-Route header field parameters, whether they are known or unknown to the UAS) and MUST maintain the order of those values.

PR for the change: https://github.com/SIPp/sipp/pull/584