Removed unused using statements

src/Microsoft.AspNet.SignalR.Core/Infrastructure/CancellationTokenExtensions.cs

@@ -1,9 +1,6 @@
 // Copyright (c) Microsoft Open Technologies, Inc. All rights reserved. See License.md in the project root for license information.
 
 using System;
-using System.Diagnostics.CodeAnalysis;
-using System.Linq.Expressions;
-using System.Reflection;
 using System.Threading;
 
 namespace Microsoft.AspNet.SignalR.Infrastructure

src/Microsoft.AspNet.SignalR.Core/PersistentConnection.cs

@@ -6,7 +6,6 @@ using System.Diagnostics;
 using System.Diagnostics.CodeAnalysis;
 using System.Globalization;
 using System.Linq;
-using System.Text;
 using System.Threading.Tasks;
 using Microsoft.AspNet.SignalR.Configuration;
 using Microsoft.AspNet.SignalR.Hosting;

src/Microsoft.AspNet.SignalR.Core/TaskAsyncHelper.cs

@@ -1,13 +1,9 @@
 // Copyright (c) Microsoft Open Technologies, Inc. All rights reserved. See License.md in the project root for license information.
 
 using System;
-using System.Collections;
-using System.Collections.Generic;
 using System.Diagnostics;
 using System.Diagnostics.CodeAnalysis;
-using System.Globalization;
 using System.Linq;
-using System.Reflection;
 using System.Threading;
 using System.Threading.Tasks;
 using Microsoft.AspNet.SignalR.Infrastructure;

src/Microsoft.AspNet.SignalR.Core/Transports/LongPollingTransport.cs

@@ -3,7 +3,6 @@
 using System;
 using System.Diagnostics;
 using System.Diagnostics.CodeAnalysis;
-using System.Threading;
 using System.Threading.Tasks;
 using Microsoft.AspNet.SignalR.Hosting;
 using Microsoft.AspNet.SignalR.Infrastructure;