Update README on Visual Studio Builds
Update README on Visual Studio Builds

Since the Visual Studio project files and the related sources have been
updated to work with Visual Studio 2013, and that the test programs do
run well there, update the README file to let people know the situation.

https://bugzilla.gnome.org/show_bug.cgi?id=754082

Distrotech/libsigcxx2,Distrotech/libsigcxx2,Distrotech/libsigcxx2