Try ipv6 version to fix issue on appveyor env

Author: rlamana

test/Client.test.js

@@ -13,7 +13,7 @@ function startProxy(port) {
   proxy.use(
     '/',
     httpProxy({
-      target: 'http://0.0.0.0:8080',
+      target: 'http://[::]:8080',
       ws: true,
       changeOrigin: true,
       proxyTimeout: 30000,
@@ -30,17 +30,15 @@ describe('Client code', () => {
     const options = {
       compress: true,
       port: 8080,
-      host: '0.0.0.0',
+      host: '::',
       disableHostCheck: true,
       hot: true,
       watchOptions: {
         poll: true,
       },
     };
     addEntries(config, options);
-    helper.start(config, options, () => {
-      setTimeout(done, 15000);
-    });
+    helper.start(config, options, done);
   });
 
   afterAll(helper.close);