Previously all IQ handlers were final. The IQ handles were processed in last-added-first order and if the IQ payload matched the handler payload, the IQ would only be passed to that handler. This conflicts with our IBBReceiveSession. When running multiple concurrent file-transfers using multiple IBBReceiveSessions there are multiple IQ handlers for IBB content; one for every transfer. This commit allows a Responder to be set as non-final. In this case unhandled IQs will not be responded with an error but returned to the IQRouter so it can pass it to the next possible IQ handler. Test-Information: Tested with ConcurrentFileTransferTest with runs multiple IBB transfers in parallel. Change-Id: I8237e234cbe5c110deaa8c3d6ba303b65fd53d00