Create LICENSE.txt

This library is a derivative work of the ideas and source code from Michael Tsikkos and James Glading, originally post here:
http://blogs.msdn.com/b/mcsuksoldev/archive/2011/08/08/writing-a-gesture-service-with-the-kinect-for-windows-sdk.aspx

The Ms-PL license appears to be the most appropriate license as a result of this derivation.