ERP5: remove a few dependencies to obsolete eggs

stack/erp5/buildout.cfg

@@ -465,7 +465,6 @@ eggs =
   chardet
   collective.recipe.template
   coverage
-  elementtree
   erp5diff
   inotifyx
   interval
@@ -489,7 +488,6 @@ eggs =
   xml_marshaller
   xupdate_processor
   feedparser
-  argparse
   validictory
   erp5.util
   huBarcode
@@ -663,7 +661,6 @@ WSGIUtils = 0.7
 astroid = 1.3.8
 chardet = 2.3.0
 csp-eventlet = 0.7.0
-elementtree = 1.2.6.post20050316
 erp5diff = 0.8.1.7
 eventlet = 0.17.4
 five.formlib = 1.0.4