remove buildout_common.cfg and adhocracy_setup_database

 It is not clear why we need buildout_common.cfg, it is quit similar to adhocarcy.cfg. It was meant to be an example how to include and customize the other buildout files. 

Also it is not clear why adhcocracy_setup_database.cfg is split from adhocarcy.cfg. The reason why was maybe you don't want the buildout to try to setup the adhcracy database.

To simplify things i propose to: 

        * merge adhcorcy_setup_database.cfg in adhocracy.cfg 
        * remove buildout_common.cfg 
        * rename the buildout_*.cfg  files to adhocracy_*.cfg