测试老师创建实验及暂存代码
测试教师修改课程
Merge commit 'd6908e857f68a5fb74011ad2c0fef662dffbca67' into feature/test_student_experiment

# By zyp (2) and others
# Via zyp
* commit 'd6908e857f68a5fb74011ad2c0fef662dffbca67':
  修改了experiment modify的一个小bug
  增加选课及退课约束
  修改了lessoncategory测试模块的后台登陆路径
  remove useless file
测试老师删除实验
小改动,基本完成对正确提交的测试
暂存
Merge branch 'develop' into feature/test_student_experiment

* develop:
  改正删除课程的bug
  修改创建实验时的返回对象
修改测试错误
Merge branch 'develop' into feature/test_student_experiment

* develop:
  修改修改实验时的返回值问题
修改缩进
时间字段改为None
把save()改成object.create()
Merge branch 'feature/test_student_experiment' into develop