test_result: fix display of durations

 - str() because in ERP5JS the duration are directly serialized to json,
   which is not allowed.
 - int() to have a second level precision, which is more readable.

bt5/erp5_test_result/SkinTemplateItem/portal_skins/erp5_test_result/TestResultLine_view/my_duration.xml

@@ -279,7 +279,7 @@
       <dictionary>
         <item>
             <key> <string>_text</string> </key>
-            <value> <string>python: modules[\'datetime\'].timedelta(seconds=context.getProperty(\'duration\'))</string> </value>
+            <value> <string>python: str(modules[\'datetime\'].timedelta(seconds=int(context.getProperty(\'duration\'))))</string> </value>
         </item>
       </dictionary>
     </pickle>

bt5/erp5_test_result/SkinTemplateItem/portal_skins/erp5_test_result/TestResult_statTestResultLineList.py

 import datetime
 from Products.PythonScripts.standard import Object
 
-return [Object(duration=datetime.timedelta(seconds=context.getProperty('duration', 0)),
+return [Object(duration=str(datetime.timedelta(seconds=int(context.getProperty('duration', 0)))),
                all_tests=context.getProperty('all_tests'),
                errors=context.getProperty('errors'),
                failures=context.getProperty('failures'),

bt5/erp5_test_result/SkinTemplateItem/portal_skins/erp5_test_result/TestResult_view/listbox_duration.xml

@@ -279,7 +279,7 @@
       <dictionary>
         <item>
             <key> <string>_text</string> </key>
-            <value> <string>python: modules[\'datetime\'].timedelta(seconds=cell.getProperty(\'duration\'))</string> </value>
+            <value> <string>python: str(modules[\'datetime\'].timedelta(seconds=int(cell.getProperty(\'duration\'))))</string> </value>
         </item>
       </dictionary>
     </pickle>