Dave D'Amico

I wasn't able to get the `AdditionalImportDirs` to work. It did not work with a non-nuget proto file either (e.g. the proto was located at c:\temp\). I ended up doing...

@roederja2 My NuGet package contains a single proto file. Adding a reference to the NuGet package adds the proto file to my csproj, but it does build a gRPC client/server....