Add Umbraco files during publish

These files will add MSBuild target that copies /umbraco /umbraco_client and /App_Browsers files to .csproj files, during install of NuGet package UmbracoCms

Functionality has been tested by creating af copy of the current Nuget package and add these files to the package, then using this package on a new Web application project. Building and doing a VS Publish to the filesystem.