feat(webpackDevServer): Add watchOptions for webpackDevServer

Add watchOptions to webpackDevServerConfiguration to conditionally enable
polling option in watchpack
Remove additional blank lines from end of serve-watchpack.ts so that only
one is remaining

addon/ng2/tasks/serve-webpack.ts

@@ -45,7 +45,10 @@ module.exports = Task.extend({
       historyApiFallback: true,
       stats: webpackDevServerOutputOptions,
       inline: true,
-      proxy: proxyConfig
+      proxy: proxyConfig,
+      watchOptions: {
+        poll: CliConfig.fromProject().defaults.poll
+      }
     };
 
     const serveMessage:string = chalk.green(`\n*\n*\n NG Live Development Server is running on http://${commandOptions.host}:${commandOptions.port}.\n*\n*`);
@@ -70,7 +73,3 @@ module.exports = Task.extend({
     })
   }
 });
-
-
-
-