MACOS: atom remote-sync with oracle vm id_rsa to pem format

前提：create vm 時使用自行上傳 public key
* cp 一份 id_rsa

cp ~/.ssh/id_rsa ~/.ssh/id_rsa_pem

* 轉換pem

ssh-keygen -p -m PEM -f ~/.ssh/id_rsa_pem

* 把 remote-sync 的keyfile 設定為 ~/.ssh/id_rsa_pem 即可