Remove unused IGitHubClient MEF export

This doesn't appear to be imported anywhere (no MEF log errors when removed).

Author: jcansdale

src/GitHub.VisualStudio/GitHubPackage.cs

@@ -1,5 +1,4 @@
 using System;
-using System.ComponentModel.Composition;
 using System.Runtime.InteropServices;
 using System.Threading;
 using System.Threading.Tasks;
@@ -8,15 +7,13 @@
 using GitHub.Extensions;
 using GitHub.Info;
 using GitHub.Logging;
-using GitHub.Models;
 using GitHub.Services;
 using GitHub.ViewModels.GitHubPane;
 using GitHub.VisualStudio.Menus;
 using GitHub.VisualStudio.UI;
 using Microsoft.VisualStudio;
 using Microsoft.VisualStudio.Shell;
 using Microsoft.VisualStudio.Shell.Interop;
-using Octokit;
 using Serilog;
 using Task = System.Threading.Tasks.Task;
 
@@ -92,16 +89,6 @@ async Task EnsurePackageLoaded(Guid packageGuid)
         }
     }
 
-    [Export(typeof(IGitHubClient))]
-    public class GHClient : GitHubClient
-    {
-        [ImportingConstructor]
-        public GHClient(IProgram program)
-            : base(program.ProductHeader)
-        {
-        }
-    }
-
     [PackageRegistration(UseManagedResourcesOnly = true, AllowsBackgroundLoading = true)]
     [ProvideService(typeof(ILoginManager), IsAsyncQueryable = true)]
     [ProvideService(typeof(IMenuProvider), IsAsyncQueryable = true)]