有时github在commit历史记录里会留下密码、用户信息等敏感记录，可以参照下边的方法删除历史记录。
1.Checkout
git checkout --orphan latest_branch
2. Add all the files
git add -A
3. Commit the changes
git commit -am "commit message"
4. Delete the branch
git branch -D master
5.Rename the current branch to master
git branch -m master
6.Finally, force update your repository
git push -f origin master
