Updating to new options pattern

src/Microsoft.AspNet.Session/SessionMiddlewareExtensions.cs

@@ -3,6 +3,7 @@
 
 using System;
 using Microsoft.AspNet.Session;
+using Microsoft.Extensions.Options;
 
 namespace Microsoft.AspNet.Builder
 {
@@ -25,5 +26,25 @@ namespace Microsoft.AspNet.Builder
 
             return app.UseMiddleware<SessionMiddleware>();
         }
+
+        /// <summary>
+        /// Adds the <see cref="SessionMiddleware"/> to automatically enable session state for the application.
+        /// </summary>
+        /// <param name="app">The <see cref="IApplicationBuilder"/>.</param>
+        /// <param name="options">The <see cref="SessionOptions"/>.</param>
+        /// <returns>The <see cref="IApplicationBuilder"/>.</returns>
+        public static IApplicationBuilder UseSession(this IApplicationBuilder app, SessionOptions options)
+        {
+            if (app == null)
+            {
+                throw new ArgumentNullException(nameof(app));
+            }
+            if (options == null)
+            {
+                throw new ArgumentNullException(nameof(options));
+            }
+
+            return app.UseMiddleware<SessionMiddleware>(Options.Create(options));
+        }
     }
 }

src/Microsoft.AspNet.Session/SessionOptions.cs

@@ -2,8 +2,9 @@
 // Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
 
 using System;
+using Microsoft.AspNet.Session;
 
-namespace Microsoft.AspNet.Session
+namespace Microsoft.AspNet.Builder
 {
     /// <summary>
     /// Represents the session state options for the application.

src/Microsoft.AspNet.Session/SessionServiceCollectionExtensions.cs

@@ -2,6 +2,7 @@
 // Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
 
 using System;
+using Microsoft.AspNet.Builder;
 using Microsoft.AspNet.Session;
 
 namespace Microsoft.Extensions.DependencyInjection
@@ -23,7 +24,6 @@ namespace Microsoft.Extensions.DependencyInjection
                 throw new ArgumentNullException(nameof(services));
             }
             
-            services.AddOptions();
             services.AddTransient<ISessionStore, DistributedSessionStore>();
             return services;
         }