EmailProcessor polls non-default mail accounts

Currently, bin/EmailProcessor.php seems to try to poll all accounts defined in civicrm_mail_settings. I'm not sure this is something we want to do (and it actually seems to break in at least some cases - see http://forum.civicrm.org/?topic=5220 - mainly the 4th page). Please consider applying the attached patch (also check how CiviMailProcessor handles this).