Drop legacy.

setuptools are pinned, and distribute is not used at all in ERP5 SlapOS
based installation.

stack/erp5.cfg

@@ -454,12 +454,6 @@ SOAPpy = 0.12.0nxd001
 # we are still using this old stable version.
 rdiff-backup = 1.0.5
 
-# Zope Known Good Set is incompatible with buildout 1.5.0 in case of
-# distribute and zc.buildout, and as ERP5 Appliance trunk wants to use
-# the newest versions of buildout infrastructure clear the pin
-distribute =
-setuptools =
-
 # official pysvn egg does not supports --include-dirs and
 # --library-dirs, so we use our modified version
 pysvn = 1.7.4nxd006