Check c++ version based on msvc version

[terrorfisch]

See #6

[terrorfisch]

Strange. The tests do not fail on my machine and dnot seem connected to the code changes.

[stefanseefeld]

I have rewritten the scheduler (using Python async), so these failures should be a thing of the past.
I don't agree with this PR, though: While I understand that MSVC may actually support C++11 now, I think it's best to preserve the semantics of these specific checks. If that doesn't yield the information you want you may think of other checks that test specific C++ features, rather than only that version macro. Else we get into the muddy waters of having to decide what it actually means to support C++11, etc.