Revert "ERP5Security: Ignore login leading- and trailing-whitespaces."

This reverts commit bf003551.
This commit will be re-applied along with necessary unit test changes.

product/ERP5Security/ERP5UserManager.py

@@ -133,7 +133,6 @@ class ERP5UserManager(BasePlugin):
             if not login or not (password or ignore_password):
                 return None
 
-            login = login.strip()
             user_list = self.getUserByLogin(login)
 
             if not user_list: