React to HttpAbstractions namespace changes

- aspnet/HttpAbstractions#549 and aspnet/HttpAbstractions#592
- clean up `using`s

Author: dougbu

src/Microsoft.AspNetCore.Hosting/WebHostBuilder.cs

@@ -12,7 +12,6 @@
 using Microsoft.AspNetCore.Hosting.Server;
 using Microsoft.AspNetCore.Hosting.Startup;
 using Microsoft.AspNetCore.Http;
-using Microsoft.AspNetCore.Http.Internal;
 using Microsoft.Extensions.Configuration;
 using Microsoft.Extensions.DependencyInjection;
 using Microsoft.Extensions.Logging;

src/Microsoft.AspNetCore.TestHost/RequestFeature.cs

@@ -4,7 +4,6 @@
 using System.IO;
 using Microsoft.AspNetCore.Http;
 using Microsoft.AspNetCore.Http.Features;
-using Microsoft.AspNetCore.Http.Internal;
 
 namespace Microsoft.AspNetCore.TestHost
 {

src/Microsoft.AspNetCore.TestHost/ResponseFeature.cs

@@ -6,7 +6,6 @@
 using System.Threading.Tasks;
 using Microsoft.AspNetCore.Http;
 using Microsoft.AspNetCore.Http.Features;
-using Microsoft.AspNetCore.Http.Internal;
 
 namespace Microsoft.AspNetCore.TestHost
 {

test/Microsoft.AspNetCore.Hosting.Tests/WebHostBuilderTests.cs

@@ -10,7 +10,6 @@
 using Microsoft.AspNetCore.Hosting.Server;
 using Microsoft.AspNetCore.Http;
 using Microsoft.AspNetCore.Http.Features;
-using Microsoft.AspNetCore.Http.Internal;
 using Microsoft.Extensions.Configuration;
 using Microsoft.Extensions.DependencyInjection;
 using Microsoft.Extensions.Logging;

test/Microsoft.AspNetCore.TestHost.Tests/ClientHandlerTests.cs

@@ -5,15 +5,13 @@
 using System.IO;
 using System.Linq;
 using System.Net.Http;
-using System.Text;
 using System.Threading;
 using System.Threading.Tasks;
 using Microsoft.AspNetCore.Builder;
 using Microsoft.AspNetCore.Hosting;
 using Microsoft.AspNetCore.Hosting.Internal;
 using Microsoft.AspNetCore.Hosting.Server;
 using Microsoft.AspNetCore.Http;
-using Microsoft.AspNetCore.Http.Internal;
 using Microsoft.AspNetCore.Http.Features;
 using Microsoft.AspNetCore.Testing.xunit;
 using Microsoft.Extensions.DependencyInjection;

test/Microsoft.AspNetCore.TestHost.Tests/TestServerTests.cs

@@ -11,11 +11,10 @@
 using Microsoft.AspNetCore.Hosting;
 using Microsoft.AspNetCore.Http;
 using Microsoft.AspNetCore.Http.Features;
-using Microsoft.AspNetCore.Http.Internal;
 using Microsoft.AspNetCore.Testing.xunit;
 using Microsoft.Extensions.DependencyInjection;
-using Microsoft.Extensions.Logging;
 using Microsoft.Extensions.DiagnosticAdapter;
+using Microsoft.Extensions.Logging;
 using Xunit;
 
 namespace Microsoft.AspNetCore.TestHost