[FAB-6350] DeliverService CI failure: serve < register

The orderer service mock in the deliver service package tries to
register a gRPC server after serve might be called.

This is forbidden in the latest gRPC version.

the error is:

17:39:38 unit-tests_1  | 2017-09-29 17:39:38.437 UTC [grpc] Fatalf -> CRIT 06a grpc: Server.RegisterService after Server.Serve for "orderer.AtomicBroadcast"
17:39:38 unit-tests_1  | FAIL	github.com/hyperledger/fabric/core/deliverservice	7.090s
17:39:38 unit-tests_1  | error: exit status 1
17:39:38 unit-tests_1  | panic: EOF

Change-Id: I04b2ccc25ba6978ad3848571030515f051f71622
Signed-off-by: yacovm <yacovm@il.ibm.com>

Author: yacovm

core/deliverservice/mocks/orderer.go

@@ -36,7 +36,6 @@ func NewOrderer(port int, t *testing.T) *Orderer {
 	if err != nil {
 		panic(err)
 	}
-	go srv.Serve(lsnr)
 	o := &Orderer{Server: srv,
 		Listener:         lsnr,
 		t:                t,
@@ -45,6 +44,7 @@ func NewOrderer(port int, t *testing.T) *Orderer {
 		stopChan:         make(chan struct{}, 1),
 	}
 	orderer.RegisterAtomicBroadcastServer(srv, o)
+	go srv.Serve(lsnr)
 	return o
 }