[VS Addin] Add visual studio 2012 support

visual_studio/NativeClientVSAddIn/UnitTests/UnitTests_2012.csproj

-<?xml version="1.0" encoding="utf-8"?>
+<?xml version="1.0" encoding="utf-8"?>
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   <PropertyGroup>
     <Configuration Condition=" '$(Configuration)' == '' ">Debug</Configuration>
     <Platform Condition=" '$(Platform)' == '' ">AnyCPU</Platform>
     <ProductVersion>
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     <ProjectGuid>{C2657776-4A69-478D-89E9-AF81FA716FF5}</ProjectGuid>
     <OutputType>Library</OutputType>
     <AppDesignerFolder>Properties</AppDesignerFolder>
     <RootNamespace>UnitTests</RootNamespace>
     <AssemblyName>UnitTests</AssemblyName>
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+    <TargetFrameworkVersion>v4.5</TargetFrameworkVersion>
     <FileAlignment>512</FileAlignment>
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+    <TargetFrameworkProfile />
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   <PropertyGroup Condition=" '$(Configuration)|$(Platform)' == 'Debug|AnyCPU' ">
     <DebugSymbols>true</DebugSymbols>
     <DebugType>full</DebugType>
     <Optimize>false</Optimize>
-    <OutputPath>..\..\..\out\vs_addin\Debug\</OutputPath>
-    <DefineConstants>DEBUG;TRACE</DefineConstants>
+    <OutputPath>..\..\..\out\vs_addin\2012\Debug\</OutputPath>
+    <DefineConstants>TRACE;DEBUG;VS2012</DefineConstants>
     <ErrorReport>prompt</ErrorReport>
     <WarningLevel>4</WarningLevel>
+    <Prefer32Bit>false</Prefer32Bit>
+    <TreatWarningsAsErrors>true</TreatWarningsAsErrors>
   </PropertyGroup>
   <PropertyGroup Condition=" '$(Configuration)|$(Platform)' == 'Release|AnyCPU' ">
     <DebugType>pdbonly</DebugType>
     <Optimize>true</Optimize>
-    <OutputPath>..\..\..\out\vs_addin\Release\</OutputPath>
+    <OutputPath>..\..\..\out\vs_addin\2012\Release\</OutputPath>
     <DefineConstants>TRACE</DefineConstants>
     <ErrorReport>prompt</ErrorReport>
     <WarningLevel>4</WarningLevel>
+    <Prefer32Bit>false</Prefer32Bit>
   </PropertyGroup>
   <ItemGroup>
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-    </Reference>
-    <Reference Include="EnvDTE100, Version=10.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a, processorArchitecture=MSIL">
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     </Reference>
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     <Reference Include="Microsoft.VisualStudio.Shell.10.0, Version=10.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a, processorArchitecture=MSIL" />
-    <Reference Include="Microsoft.VisualStudio.VCProject, Version=10.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a">
+    <Reference Include="Microsoft.VisualStudio.VCProject, Version=11.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a">
       <EmbedInteropTypes>True</EmbedInteropTypes>
     </Reference>
-    <Reference Include="Microsoft.VisualStudio.VCProjectEngine, Version=10.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a">
+    <Reference Include="Microsoft.VisualStudio.VCProjectEngine, Version=11.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a">
       <EmbedInteropTypes>True</EmbedInteropTypes>
     </Reference>
     <Reference Include="stdole, Version=7.0.3300.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a">
       <EmbedInteropTypes>False</EmbedInteropTypes>
     </Reference>
     <Reference Include="System" />
     <Reference Include="System.Core">
       <RequiredTargetFramework>3.5</RequiredTargetFramework>
     </Reference>
     <Reference Include="System.Data" />
@@ skipping 23 matching lines @@
     <Compile Include="WebServerTest.cs" />
   </ItemGroup>
   <ItemGroup>
     <Shadow Include="Test References\NativeClientVSAddIn.accessor" />
   </ItemGroup>
   <ItemGroup>
     <ProjectReference Include="..\NaCl.Build.CPPTasks\NaCl.Build.CPPTasks.csproj">
       <Project>{FCD6F8FE-DF89-4232-A138-42C97826712A}</Project>
       <Name>NaCl.Build.CPPTasks</Name>
     </ProjectReference>
-    <ProjectReference Include="..\NativeClientVSAddIn\NativeClientVSAddIn.csproj">
+    <ProjectReference Include="..\NativeClientVSAddIn_2012\NativeClientVSAddIn_2012.csproj">
       <Project>{16A0B3E3-6E53-430B-B388-3811E09FC7B8}</Project>
       <Name>NativeClientVSAddIn</Name>
       <EmbedInteropTypes>False</EmbedInteropTypes>
     </ProjectReference>
   </ItemGroup>
   <Import Project="$(MSBuildBinPath)\Microsoft.CSharp.targets" />
   <!-- To modify your build process, add your task inside one of the targets below and uncomment it. 
        Other similar extension points exist, see Microsoft.Common.targets.
   <Target Name="BeforeBuild">
   </Target>
   <Target Name="AfterBuild">
   </Target>
   -->
-</Project>
+</Project>