Add an 'ssh' shared folder mounted at /etc/ssh/authorized_keys/
To point sshd at the correct authorized_keys location and to allow for shared_folders limited username/permissions mapping :
  sed -i 's/.*StrictModes.*/StrictModes no/' /etc/ssh/sshd_config
  sed -i 's^.*AuthorizedKeysFile.*^AuthorizedKeysFile      /etc/ssh/authorized_keys/%u/authorized_keys^' /etc/ssh/sshd_config

Signed-off-by: David Greaves <david.greaves@jollamobile.com>