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.
To me, it is either you define the override but then define the corresponding osdeps, or remove the override. This half-baked definitions really makes no sense.

In particular because autoproj should validate the package and osdeps name when you define the override (https://github.com/rock-core/autoproj/issues/26)