[FAB-3643] respect peer.gossip.endpoint configuration

This patch re-adds processing that optionally assigns
peer.gossip.endpoint to our internal endpoint representation.

Without this, enabling TLS is difficult because we cannot
control the endpoint representation at runtime in a deterministic
manner.  The end result is that x509 CN/SAN validation is
likely to fail and thus our endpoint is unreachable.

Fixes FAB-3643

Change-Id: Idd52bf55d86f87160ba508329ce379d1f3be5d04
Signed-off-by: Greg Haskins <gregory.haskins@gmail.com>

gossip/service/gossip_service.go

@@ -135,6 +135,10 @@ func InitGossipServiceCustomDeliveryFactory(peerIdentity []byte, endpoint string
 	factory DeliveryServiceFactory, mcs api.MessageCryptoService, secAdv api.SecurityAdvisor,
 	secureDialOpts api.PeerSecureDialOpts, bootPeers ...string) {
 	once.Do(func() {
+		if overrideEndpoint := viper.GetString("peer.gossip.endpoint"); overrideEndpoint != "" {
+			endpoint = overrideEndpoint
+		}
+
 		logger.Info("Initialize gossip with endpoint", endpoint, "and bootstrap set", bootPeers)
 
 		idMapper := identity.NewIdentityMapper(mcs)