Reverted to old setup.py in preparation for packaging.

buildsupport/README.txt

-zpkg support files
-==================
-
-Files and packages included here are intended to support the use of
-zpkg as a build tool.  They are not part of Zope, are not included in
-the distribution, and are not importable in the application server.
-
-The setup.py script will process any .pth files placed here, though
-those would not normally be handled by most applications.

buildsupport/zpkg-support.pth

-# This allows the ZConfig checked out with Zope to be used by the zpkg
-# code invoked by setup.py.
-#
-# If zpkg ever requires a different version of ZConfig than Zope
-# provides as part of it's checkout, this file should be replaced by
-# an svn:external to the required version.
-#
-../src