Handling abnormal sync failures (and hopefully preventing SF dupes)

Added handling of abnormal sync failures to hook_salesforce_sync_fail_item() implementation in salesforce_queue.module. Exceptions without SF faultcodes, and result objects without statusCodes will be sent directly to the fail queue, to prevent potential dupes in SF, and the abnormalities will be logged. Added new "salesforce_queue_abnormal_failure" Rules event to salesforce_queue module to provide abnormal sync failure alerts.