Expose one more libcurl option: CURLOPT_SSH_HOST_PUBLIC_KEY_MD5. This allows authenticating the server by the MD5 fingerprint of the server's public key. https://bugzilla.gnome.org/show_bug.cgi?id=723167
https://bugzilla.gnome.org/show_bug.cgi?id=728960
Note: SFTP = SSH File Transfer Protocol The sink acts as a client and uploads data to the SFTP server. https://bugzilla.gnome.org/show_bug.cgi?id=709795