成员替换，创建会话，人员先删除后写入

src/server/models/sessions/topics.js

@@ -112,11 +112,14 @@ class Topics extends RedisModel {
            if (err || res.length == 0) {
                ModelUtil.emitOK(self.eventEmitter, {status: -1, message: "找不到对应的会话记录！"});
            }
            if(!res[0].session_id){
                ModelUtil.emitOK(self.eventEmitter, {status: -1, message: err});
            }
            let sessions = new Sessions();
            sessions.getMessages(res[0].session_id, user, startMsgId, endMsgId, page, pagesize, 0, function (err, messages) {
                if (err) {
                    ModelUtil.emitOK(self.eventEmitter, {status: -1, message: err});
                    ModelUtil.emitOK(self.eventEmitter, {status: 200, data: {"list":[],"users":[]}});
                } else {
                    if (messages && messages.length > 0) {
                        ParticipantRepo.findAll(res[0].session_id, function (err, users) {