change workid to participantId

mooctest-site-server/src/main/java/cn/iselab/mooctest/site/service/impl/GroupServiceImpl.java

@@ -267,7 +267,7 @@ public class GroupServiceImpl implements GroupService {
         //add Group2Worker
         Group2Worker group2Worker = new Group2Worker();
         group2Worker.setGroupId(group.getId());
-        group2Worker.setWorkerId(id);
+        group2Worker.setParticipantId(id);
         group2Worker.setRecordCreateTime(new Timestamp(System.currentTimeMillis()));
         group2WorkerDao.save(group2Worker);