Only store major version of AddIn in VS project file

visual_studio/NativeClientVSAddIn/NativeClientVSAddIn/Utility.cs

Index: visual_studio/NativeClientVSAddIn/NativeClientVSAddIn/Utility.cs
diff --git a/visual_studio/NativeClientVSAddIn/NativeClientVSAddIn/Utility.cs b/visual_studio/NativeClientVSAddIn/NativeClientVSAddIn/Utility.cs
index 94dff83c2641588b12fba54347c261b7476bfd48..cdc93e7bebbcd22e4c90d917001eb683539f797e 100644
--- a/visual_studio/NativeClientVSAddIn/NativeClientVSAddIn/Utility.cs
+++ b/visual_studio/NativeClientVSAddIn/NativeClientVSAddIn/Utility.cs
@@ -23,6 +23,10 @@ namespace NativeClientVSAddIn
     /// <returns>True if project is a Visual C/C++ project.</returns>
     public static bool IsVisualCProject(Project proj)
     {
+      if (proj.Properties == null)
+      {
+        return false;
+      }
       foreach (Property prop in proj.Properties)
       {
         if (prop.Name == "Kind")