Improved firstuse wizard. Using improved clientlib logging.

 * clientlib logging is now hooked into Play!s logging mechanism, so the log
   messages will appear in application.log.
 * The temporary directory and result directory settings are moved from
   the Pipeline 2 Web API form into the Storage Directory form.
 * The Pipeline 2 Web API setup form now checks whether the endpoint you
   entered is valid, and up-and-running. Authentication options are only
   displayed when the endpoint reports that it requires authentication.
 * "Popular" endpoint URLs are tried automatically and suggested if
   available. Currently http://localhost:8181/ws and
   http://localhost:8182/ws is tried.