big refactoring of visual studio projects, started using nuget

vsprojects/Grpc.mak

vsprojects/README

vsprojects/README.md

vsprojects/global.props

vsprojects/gpr/gpr.vcxproj

vsprojects/gpr/gpr.vcxproj.filters

vsprojects/gpr_test_util/gpr_test_util.vcxproj

vsprojects/grpc++/grpc++.vcxproj

vsprojects/grpc++/grpc++.vcxproj.filters

vsprojects/grpc.sln

vsprojects/grpc/grpc.vcxproj

vsprojects/grpc/grpc.vcxproj.filters

vsprojects/grpc/packages.config

vsprojects/grpc_csharp_ext/grpc_csharp_ext.vcxproj

vsprojects/grpc_csharp_ext/packages.config

vsprojects/grpc_test_util/grpc_test_util.vcxproj

vsprojects/grpc_unsecure/grpc_unsecure.vcxproj

vsprojects/grpc_unsecure/grpc_unsecure.vcxproj.filters

vsprojects/grpc_unsecure/packages.config

vsprojects/make.bat