Update KinectSkeletonViewer.xaml.cs

I got the fix from here:
http://stackoverflow.com/questions/15693056/mapfromskeletonpoint-obsolete-in-kinect

I replaced the lines @ 172 and 177 with the ones from the forum.

I supressed the error warnings that were left and the app "worked". I have not gotten it fully functional yet, but I will make time for that very soon.