use view image method to render thumbnail

git-svn-id: https://svn.erp5.org/repos/public/erp5/trunk@5962 20353a03-c40f-0410-a6d1-a30d3c3de9de

bt5/erp5_base/SkinTemplateItem/portal_skins/erp5_base/Agent_view/Image_view.xml

@@ -315,7 +315,7 @@
       <dictionary>
         <item>
             <key> <string>_text</string> </key>
-            <value> <string>here/absolute_url</string> </value>
+            <value> <string>python: here.absolute_url() + \'/viewImage\'</string> </value>
         </item>
       </dictionary>
     </pickle>