protocol_acceptor: Make SSL handshake asynchronous

Change-Id: Ia8808633344389297fe026cd2219aa513f6f1dff
Signed-off-by: Saggi Mizrahi <smizrahi@redhat.com>
Reviewed-on: http://gerrit.ovirt.org/33657
Tested-by: Martin Peřina <mperina@redhat.com>
Reviewed-by: Piotr Kliczewski <piotr.kliczewski@gmail.com>
Reviewed-by: Dan Kenigsberg <danken@redhat.com>