Moved kinect to github, moved freenect to drivers, build freenect only on ubuntu

Not sure for the Version checking how this should be done currently.
The current realization is working but seems a bit ugly.
There's no straightforward way, no. Currently, the user would have to call add_osdeps_overrides in its overrides.rb file manually. We would have to add a way to force the use of source packages in the manifest.

Do define the osdep, though. Just add force: true to the add_osdeps_overrides line to force the use of the source package.