Add your public key to https://github.com/settings/ssh.
mkdir git
cd git
git clone https://github.com/birnenlabs/chrome-extensions
cd chrome-extensions
git remote set-url origin git+ssh://git@github.com/birnenlabs/chrome-extensions
git add -A
git commit -am "Update README.md"
git push
zip -r extension.zip ./${extension_dir}