CoreApp doesn't generate a WinMD (#426)

vsix/ProjectTemplates/VC/Windows Universal/CoreApp/CoreApp.vcxproj

@@ -3,7 +3,6 @@
   <PropertyGroup Label="Globals">
     <CppWinRTOptimized>true</CppWinRTOptimized>
     <CppWinRTRootNamespaceAutoMerge>true</CppWinRTRootNamespaceAutoMerge>
-    <CppWinRTGenerateWindowsMetadata>true</CppWinRTGenerateWindowsMetadata>
     <MinimalCoreWin>true</MinimalCoreWin>
     <ProjectGuid>{$guid1$}</ProjectGuid>
     <ProjectName>$projectname$</ProjectName>
@@ -129,4 +128,4 @@
   <Import Project="$(VCTargetsPath)\Microsoft.Cpp.targets" />
   <ImportGroup Label="ExtensionTargets">
   </ImportGroup>
-</Project>
+</Project>