Use RelayCommand from TeamFoundation assembly

This avoids loading the GitHub.Extensions and GitHub.Exports assemblies.

Author: jcansdale

src/GitHub.VisualStudio.16/Sync/PublishSection.cs

@@ -7,14 +7,14 @@
 using System.Windows.Input;
 using GitHub.Extensions;
 using GitHub.Factories;
-using GitHub.Primitives;
 using GitHub.Services;
 using GitHub.ViewModels.TeamExplorer;
 using Microsoft.TeamFoundation.Controls;
 using Microsoft.VisualStudio.Shell;
 using Microsoft.VisualStudio.Threading;
 using ReactiveUI;
 using Task = System.Threading.Tasks.Task;
+using RelayCommand = Microsoft.TeamFoundation.MVVM.RelayCommand;
 
 
 namespace GitHub.VisualStudio.Sync