Fix PermissionHandler test failure, fix #293

Modify the PermissionHandler test client to bind to the default
localhost IPv4 address, 127.0.0.1, instead of 127.0.0.33 that may not
be up by default on certain platforms. The client IP 127.0.0.33 was
chosen originally to minimize interference with existing tests.

Author: rg0now

server_test.go

@@ -133,7 +133,7 @@ func TestServer(t *testing.T) {
 						Address:      "0.0.0.0",
 					},
 					PermissionHandler: func(src net.Addr, peer net.IP) bool {
-						return src.String() == "127.0.0.33:54321" &&
+						return src.String() == "127.0.0.1:54321" &&
 							peer.Equal(net.ParseIP("127.0.0.4"))
 					},
 				},
@@ -144,7 +144,7 @@ func TestServer(t *testing.T) {
 		assert.NoError(t, err)
 
 		// enforce corrent client IP and port
-		conn, err := net.ListenPacket("udp4", "127.0.0.33:54321")
+		conn, err := net.ListenPacket("udp4", "127.0.0.1:54321")
 		assert.NoError(t, err)
 
 		client, err := NewClient(&ClientConfig{