Support for Windows 7

Changes:

• 0651af8 Build tweaks to simplify Win7 smoke testing (#471)
• a2c65b4 Support for Windows 7 (#469)
• 39d65cb guid (#467)
• d6c9ee9 Specialize std::hash for winrt::guid (#466)
• 1a54011 Implement operator< for winrt::guid (#464)

This list of changes was auto generated.