- change SimpleItem.py to use python logging module
  - log at error when standard_error_message can't be rendered
  - give more useful info about errors rendering standard_error_message to the browser.
  - all conflict errors are counted and logged at info
  - logging makes it clear where the conflict has been resolved and where it hasn't
  - errors seen by the user are rendered with standard_error_message and are sent to the error_log which will likely copy them to the event log, depending on the users setup.
  - also checking in a functional test for generating write conflict errors.
    
  (I'll be committing to CHANGES.TXT shortly, I just wanted to keep the merges simpler)