为Bootstrap模态对话框添加拖拽移动功能

参考链接：

https://blog.csdn.net/hnllc2012/article/details/50607884?utm_medium=distribute.pc_relevant_t0.none-task-blog-BlogCommendFromMachineLearnPai2-1.control&depth_1-utm_source=distribute.pc_relevant_t0.none-task-blog-BlogCommendFromMachineLearnPai2-1.control