Generic Version with conditioanl Gnome and Unity support

This is a version of current master, which compiles and runs with Ubuntu Trusty. 
It is basically patched with the patches from 
http://www.webupd8.org/2013/10/install-nemo-with-unity-patches-and.html 
So all credits are going to Jacob Zimmermann. 

I have added conditional compiling for Unity, Gnome and Zeitgeist, in a way that it would be possible to maintain this in master branch. 
It should still work with Cinnamon without any issues.