Reorganize source code in preparation to move into aspnet/AspNetCore

src/CORS/NuGetPackageVerifier.json

src/CORS/README.md

src/CORS/build/Key.snk

src/CORS/build/buildpipeline/linux.groovy

src/CORS/build/buildpipeline/osx.groovy

src/CORS/build/buildpipeline/pipeline.groovy

src/CORS/build/buildpipeline/windows.groovy

src/CORS/build/dependencies.props

src/CORS/build/repo.props

src/CORS/build/repo.targets

src/CORS/build/sources.props

src/CORS/samples/README.md

src/CORS/samples/SampleDestination/Program.cs

src/CORS/samples/SampleDestination/SampleDestination.csproj

src/CORS/samples/SampleDestination/SampleMiddleware.cs

src/CORS/samples/SampleDestination/Startup.cs

src/CORS/samples/SampleOrigin/Program.cs

src/CORS/samples/SampleOrigin/SampleOrigin.csproj

src/CORS/samples/SampleOrigin/Startup.cs

src/CORS/samples/SampleOrigin/wwwroot/index.htm