React to ServerFactory changes.

src/MusicStore/Program.cs

@@ -1,5 +1,4 @@
 using System;
-using System.Threading.Tasks;
 using Microsoft.AspNet.Hosting;
 using Microsoft.Extensions.Configuration;
 
@@ -19,7 +18,7 @@ namespace MusicStore
             var config = builder.Build();
 
             using (new WebHostBuilder(config)
-                .UseServer("Microsoft.AspNet.Server.WebListener")
+                .UseServerFactory("Microsoft.AspNet.Server.WebListener")
                 .Build()
                 .Start())
             {

test/E2ETests/Implementation/Validator.cs

@@ -96,6 +96,7 @@ namespace E2ETests
             _logger.LogInformation("Fetching favicon.ico..");
             var response = await _httpClient.GetAsync("favicon.ico");
             await ThrowIfResponseStatusNotOk(response);
+            Assert.NotNull(response.Headers.ETag);
             _logger.LogInformation("Etag received: {etag}", response.Headers.ETag.Tag);
 
             //Check if you receive a NotModified on sending an etag