Fixed build break due to missing reference on Dev15

Author: billti

Nodejs/Product/InteractiveWindow/InteractiveWindow.csproj

@@ -101,6 +101,9 @@
     <When Condition="$(VSTarget) == '15.0'">
       <ItemGroup>
         <Reference Include="Microsoft.VisualStudio.Shell.Framework, Version=$(VSTarget).0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a" />
+        <Reference Include="Microsoft.VisualStudio.Utilities, Version=$(VSTarget).0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a" >
+            <HintPath>$(DevEnvDir)\Microsoft.VisualStudio.Utilities.dll</HintPath>
+        </Reference>
       </ItemGroup>
     </When>
     <Otherwise>