Revert "Add NuGet assemblies to the list of well-known assemblies."
Revert "Add NuGet assemblies to the list of well-known assemblies."

This reverts commit 183645c502cc41de4b63662704b7b339c32f0f12.

rainersigwald/msbuild,AndyGerlicher/msbuild,sean-gilliam/msbuild,mono/msbuild,mono/msbuild,sean-gilliam/msbuild,sean-gilliam/msbuild,AndyGerlicher/msbuild,rainersigwald/msbuild,mono/msbuild,rainersigwald/msbuild,AndyGerlicher/msbuild,mono/msbuild,AndyGerlicher/msbuild,sean-gilliam/msbuild,rainersigwald/msbuild