Fixes for compiling BlockOpenNISkeleton sample on OSX (10.8)

[heisters]

These are a few of the changes I had to make to get the sample compiling. Using OSX 10.8, latest drivers (OpenNI 1.5.4.0, Sensor 5.1.2.1, NITE 1.5.2.21).

I had to do a couple other things too, but I figured they were too controversial or specific to my setup for a pull request. Nevertheless, for the sake of completeness, they were:

1. copy *.h from src/ to include/Include
2. fix paths in the XCode project for my local environment and what appears to be a changed directory structure (eg. Lib -> lib/macosx and Include -> include/Include).

[heisters]

Ignore the first item on there. The sample project had lost the locations of the header files. Once that was fixed I could remove the headers from the include directory.