Remove useless code

Author: shana

src/GitHub.App/ViewModels/LoginControlViewModel.cs

@@ -48,7 +48,6 @@ public LoginControlViewModel(
             AuthenticationResults = Observable.Merge(
                 loginToGitHubViewModel.Login,
                 EnterpriseLogin.Login);
-            CancelCommand = ReactiveCommand.Create();
         }
 
         ILoginToGitHubViewModel github;

src/GitHub.App/ViewModels/PullRequestListViewModel.cs

@@ -41,7 +41,6 @@ public PullRequestListViewModel(IRepositoryHost repositoryHost, ISimpleRepositor
             this.repositoryHost = repositoryHost;
             this.repository = repository;
 
-            CancelCommand = ReactiveCommand.Create();
             openPullRequestCommand = ReactiveCommand.Create();
             openPullRequestCommand.Subscribe(_ =>
             {

src/GitHub.App/ViewModels/TwoFactorDialogViewModel.cs

@@ -42,7 +42,6 @@ public TwoFactorDialogViewModel(
                 (code, busy) => !string.IsNullOrEmpty(code.Value) && code.Value.Length == 6 && !busy.Value);
 
             OkCommand = ReactiveCommand.Create(canVerify);
-            CancelCommand = ReactiveCommand.Create();
             NavigateLearnMore = ReactiveCommand.Create();
             NavigateLearnMore.Subscribe(x => browser.OpenUrl(GitHubUrls.TwoFactorLearnMore));
             //TODO: ShowHelpCommand.Subscribe(x => browser.OpenUrl(twoFactorHelpUri));

src/GitHub.VisualStudio/UI/Views/LoggedOutViewModel.cs

@@ -9,10 +9,8 @@ namespace GitHub.VisualStudio.UI.Views
     [PartCreationPolicy(CreationPolicy.NonShared)]
     public class LoggedOutViewModel : BaseViewModel
     {
-        [ImportingConstructor]
         public LoggedOutViewModel()
         {
-            CancelCommand = ReactiveCommand.Create();
         }
     }
 }