Bug 545 - Added exemplary TLS configuration

 - uncommenting the code takes effect only after https://git.opendaylight.org/gerrit/#/c/9225/ is merged
   and keys are used inside mininet for tls communication

Change-Id: I4397d094a35a429f8393466b6d69ae700a61cc4a
Signed-off-by: Michal Polkorab <michal.polkorab@pantheon.sk>