ovsdb-server: Add the ability to push peer-cert.

ovsdb-server: Add the ability to push peer-cert.

In OVN, ovsdb-server is the daemon that manages the databases
and can be called as the central controller. So it would be
nice for ovsdb-server to be able to push its self-signed
certificate to all the other nodes where ovn-controller runs.

Signed-off-by: Gurucharan Shetty <gshetty@nicira.com>
Acked-by: Ben Pfaff <blp@nicira.com>