Move remaining feature interfaces into `Microsoft.AspNetCore.Http.Features` package and namespace

- #590, also related to #561
- move feature interfaces from `Microsoft.AspNetCore.Http` package
- move required classes from `Microsoft.AspNetCore.Http.Abstractions` package
- move `ISession` and `WebSocketAcceptContext` to `Microsoft.AspNetCore.Http` namespace (#590)

nit: remove transient dependencies listed in `Microsoft.AspNetCore.Http.Abstractions`'s `project.json`

src/Microsoft.AspNetCore.Http.Abstractions/project.json

@@ -29,10 +29,8 @@
     },
     "netstandard1.3": {
       "dependencies": {
-        "System.ComponentModel": "4.0.1-*",
         "System.Globalization.Extensions": "4.0.1-*",
         "System.Linq.Expressions": "4.0.11-*",
-        "System.Net.WebSockets": "4.0.0-*",
         "System.Reflection.TypeExtensions": "4.1.0-*",
         "System.Runtime.InteropServices": "4.1.0-*"
       },

src/Microsoft.AspNetCore.Http.Extensions/SessionExtensions.cs

@@ -2,7 +2,6 @@
 // Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
 
 using System.Text;
-using Microsoft.AspNetCore.Http.Features;
 
 namespace Microsoft.AspNetCore.Http
 {

src/Microsoft.AspNetCore.Http.Features/IFormFeature.cs

@@ -4,7 +4,7 @@
 using System.Threading;
 using System.Threading.Tasks;
 
-namespace Microsoft.AspNetCore.Http.Features.Internal
+namespace Microsoft.AspNetCore.Http.Features
 {
     public interface IFormFeature
     {

src/Microsoft.AspNetCore.Http.Features/IItemsFeature.cs

@@ -3,7 +3,7 @@
 
 using System.Collections.Generic;
 
-namespace Microsoft.AspNetCore.Http.Features.Internal
+namespace Microsoft.AspNetCore.Http.Features
 {
     public interface IItemsFeature
     {

src/Microsoft.AspNetCore.Http.Features/IQueryCollection.cs

@@ -73,7 +73,8 @@ namespace Microsoft.AspNetCore.Http
         ///     The key of the value to get.
         /// </param>
         /// <returns>
-        ///     The element with the specified key, or <see cref="T:Microsoft.Extensions.Primitives.StringValues" />.Empty if the key is not present.
+        ///     The element with the specified key, or <see cref="T:Microsoft.Extensions.Primitives.StringValues" />.
+        ///     Empty if the key is not present.
         /// </returns>
         /// <exception cref="T:System.ArgumentNullException">
         ///     key is null.

src/Microsoft.AspNetCore.Http.Features/IQueryFeature.cs

@@ -1,7 +1,7 @@
 // Copyright (c) .NET Foundation. All rights reserved.
 // Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
 
-namespace Microsoft.AspNetCore.Http.Features.Internal
+namespace Microsoft.AspNetCore.Http.Features
 {
     public interface IQueryFeature
     {

src/Microsoft.AspNetCore.Http.Features/IRequestCookiesFeature.cs

@@ -1,7 +1,7 @@
 // Copyright (c) .NET Foundation. All rights reserved.
 // Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
 
-namespace Microsoft.AspNetCore.Http.Features.Internal
+namespace Microsoft.AspNetCore.Http.Features
 {
     public interface IRequestCookiesFeature
     {

src/Microsoft.AspNetCore.Http.Features/IResponseCookiesFeature.cs

@@ -1,7 +1,7 @@
 // Copyright (c) .NET Foundation. All rights reserved.
 // Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
 
-namespace Microsoft.AspNetCore.Http.Features.Internal
+namespace Microsoft.AspNetCore.Http.Features
 {
     public interface IResponseCookiesFeature
     {

src/Microsoft.AspNetCore.Http.Features/IServiceProvidersFeature.cs

@@ -3,7 +3,7 @@
 
 using System;
 
-namespace Microsoft.AspNetCore.Http.Features.Internal
+namespace Microsoft.AspNetCore.Http.Features
 {
     public interface IServiceProvidersFeature
     {

src/Microsoft.AspNetCore.Http.Features/ISession.cs

@@ -4,7 +4,7 @@
 using System.Collections.Generic;
 using System.Threading.Tasks;
 
-namespace Microsoft.AspNetCore.Http.Features
+namespace Microsoft.AspNetCore.Http
 {
     public interface ISession
     {

src/Microsoft.AspNetCore.Http.Features/WebSocketAcceptContext.cs

@@ -1,7 +1,7 @@
 // Copyright (c) .NET Foundation. All rights reserved.
 // Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
 
-namespace Microsoft.AspNetCore.Http.Features
+namespace Microsoft.AspNetCore.Http
 {
     public class WebSocketAcceptContext
     {

src/Microsoft.AspNetCore.Http.Features/project.json

@@ -21,6 +21,7 @@
     "netstandard1.3": {
       "dependencies": {
         "System.Collections": "4.0.11-*",
+        "System.ComponentModel": "4.0.1-*",
         "System.Linq": "4.1.0-*",
         "System.Net.Primitives": "4.0.11-*",
         "System.Net.WebSockets": "4.0.0-*",

src/Microsoft.AspNetCore.Owin/OwinEnvironment.cs

@@ -16,9 +16,9 @@ using System.Threading;
 using System.Threading.Tasks;
 using Microsoft.AspNetCore.Http;
 using Microsoft.AspNetCore.Http.Features;
-using Microsoft.AspNetCore.Http.Features.Internal;
 using Microsoft.AspNetCore.Http.Features.Authentication;
 using Microsoft.AspNetCore.Http.Features.Authentication.Internal;
+using Microsoft.AspNetCore.Http.Features.Internal;
 
 namespace Microsoft.AspNetCore.Owin
 {

src/Microsoft.AspNetCore.Owin/WebSockets/OwinWebSocketAcceptAdapter.cs

@@ -5,7 +5,7 @@ using System;
 using System.Collections.Generic;
 using System.Net.WebSockets;
 using System.Threading.Tasks;
-using Microsoft.AspNetCore.Http.Features;
+using Microsoft.AspNetCore.Http;
 
 namespace Microsoft.AspNetCore.Owin
 {

src/Microsoft.AspNetCore.Owin/WebSockets/OwinWebSocketAcceptContext.cs

@@ -2,7 +2,7 @@
 // Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
 
 using System.Collections.Generic;
-using Microsoft.AspNetCore.Http.Features;
+using Microsoft.AspNetCore.Http;
 
 namespace Microsoft.AspNetCore.Owin
 {

src/Microsoft.AspNetCore.Owin/WebSockets/WebSocketAcceptAdapter.cs

@@ -6,7 +6,7 @@ using System.Collections.Generic;
 using System.Net.WebSockets;
 using System.Threading;
 using System.Threading.Tasks;
-using Microsoft.AspNetCore.Http.Features;
+using Microsoft.AspNetCore.Http;
 
 namespace Microsoft.AspNetCore.Owin
 {

test/Microsoft.AspNetCore.Http.Tests/DefaultHttpContextTests.cs

@@ -8,7 +8,6 @@ using System.Net.WebSockets;
 using System.Reflection;
 using System.Security.Claims;
 using System.Threading.Tasks;
-using Microsoft.AspNetCore.Http.Authentication.Internal;
 using Microsoft.AspNetCore.Http.Features;
 using Microsoft.AspNetCore.Http.Features.Internal;
 using Xunit;