ParticipantGmsImpl.handleJoinResponse ignores the digest

... so we can install a view but there may be members of that view - including maybe even the coordinator - not in NAKACK2's xmit_table.

I think that this can be fixed by changing ParticipantGmsImpl.handleJoinResponse() so that

            gms.installView(v);

becomes

            Digest d=join_rsp.getDigest();
            gms.installView(v, d);