enable audio for winrt / UWP

[dafx]

Looks like audio is not enabled for winrt now.

In audio/Conext.cpp,

#elif defined( CINDER_MSW ) && ( _WIN32_WINNT >= 0x0600 ) // Windows Vista+
    #define CINDER_AUDIO_WASAPI
    #include "cinder/audio/msw/ContextWasapi.h"
    #include "cinder/audio/msw/DeviceManagerWasapi.h"
#else
    #define CINDER_AUDIO_DISABLED
#endif

[richardeakin]

Thanks for opening this. We've looked into it and there is work in progress, however we need to figure out how to navigate WinRT / UWP's restrictions on blocking calls - they require async operations for things like initializing an audio device.