build.proj

<Project ToolsVersion="4.0"
         DefaultTargets="Go"
         xmlns="http://schemas.microsoft.com/developer/msbuild/2003">
  <!--Import Project="$(MSBuildExtensionsPath)\MSBuildCommunityTasks\MSBuild.Community.Tasks.Targets" /-->
  <PropertyGroup>
    <GoDependsOn>PrepareNuGetFiles;Package</GoDependsOn>
    <BuildDirectory>_packaged_output\</BuildDirectory>
    <BuildPath>$(MSBuildProjectDirectory)\$(BuildDirectory)</BuildPath>
    <NuGetDirectory>$(MSBuildProjectDirectory)\nuget</NuGetDirectory>
  </PropertyGroup>

  <Target Name="Go" DependsOnTargets="$(GoDependsOn)" />
  
  <Target Name="PrepareNuGetFiles">
   <ItemGroup>
      <NuGetFiles Include="$(NuGetDirectory)\**\*" />
    </ItemGroup>
    <Copy SourceFiles="@(NuGetFiles)"
      DestinationFiles="@(NuGetFiles->'$(BuildPath)\nuget\%(RecursiveDir)%(Filename)%(Extension)')"
      Retries="3"
      RetryDelayMilliseconds="300" 
      />
  </Target>
  
  <Target Name="Package">
  <ItemGroup>
      <NuspecFiles Include="$(BuildPath)**\*nuspec" />
      <FilesToDelete Exclude="$(BuildPath)\**\*.nupkg" Include="$(BuildPath)\**\*" />
      <DirectoriesToDelete Include="$(BuildPath)\nuget" />
    </ItemGroup>
    <Exec Command="nuget pack %(NuspecFiles.FullPath)" WorkingDirectory="$(BuildPath)" />
          
    <Delete Files="@(FilesToDelete)" />
    <RemoveDir Directories="@(DirectoriesToDelete)" />
  </Target>

</Project>