hi, this patch add ssl/tls support to relocation:

 * SSL/TLS support is disabled by default, as other server did.

 * If "xend-relocation-server-ssl-key-file" and
   "xend-relocation-server-ssl-cert-file" exist, SSL/TLS is enabled
   automatically.

 * "xend-relocation-tls" is used by relocation client only.

Signed-off-by: Zhigang Wang <zhigang.x.wang@oracle.com>