OSTree Support

We need the ostree admin CLI to support the following SSL credentials on 'repo create':

  --feed-ca-cert    - full path to the CA certificate that should be used to
                      verify the external repo server's SSL certificate
  --verify-feed-ssl - if "true", the feed's SSL certificate will be verified
                      against the feed_ca_cert
  --feed-cert       - full path to the certificate to use for authorization when
                      accessing the external feed
  --feed-key        - full path to the private key for feed_cert
  --gpg-key         - used to verify the GPG signed commits pulled

and add them to the import configuration.

Further, we need to remove:

  --validate - if "true", the size and checksum of each synchronized file will
               be verified against the repo metadata

Because it does not apply to OSTree.