Port written in C++/WinRT available

[johanlindfors]

This is not really an issue, but a discussion I would like to raise. I have spent some time on porting this SDK to C++/WinRT in an external repository available here: https://github.com/coderox/FacebookSDK

My initial approach was to do a file by file migration, however I have made some changes as well (changed namespace to FacebookSDK for example) but I do believe it's in feature parity.

Please clone/fork/comment and I'd be happy to continue/evolve this iteration.