Adding buoy model with textures

I have made a navigation buoy. The Idea was inspired by the buoys in oolite, the model is completely new.
Screenshot:
* Buoy in the red blinking phase
http://ompldr.org/vaGthZA/buoy_modelr.png
* Buoy in the green blinking phase
http://ompldr.org/vaGthZg/buoy_modelg.png