transfer github repo and change committers email

mixture of these:

https://help.github.com/articles/importing-a-git-repository-using-the-command-line/
https://help.github.com/articles/changing-author-info/#platform-linux/



1. clone the old repo with bare

git clone --bare https://external-host.com/extuser/repo.git foo
cd foo

2. use this github script

https://help.github.com/articles/changing-author-info/#platform-linux
and change the variables

3. create a new github repo

4. push to the new repo

git push --mirror https://github.com/ghuser/repo.git