Updated url to point to github

Author: Jaben

src/Papercut.UI/ViewModels/MainViewModel.cs

@@ -258,7 +258,7 @@ void SetupObservables()
 
         public void GoToSite()
         {
-            Process.Start("http://papercut.codeplex.com/");
+            Process.Start("https://github.com/ChangemakerStudios/Papercut");
         }
 
         public void ShowRulesConfiguration()
@@ -375,4 +375,4 @@ protected override void OnViewAttached(object view, object context)
             }
         }
     }
-}
+}