Add nonce to purchase log action callback links.
Purchase log action link AJAX expects to receive a boolean success attribute in response object.
Add nonce to individual purchase log action AJAX callbacks.
Force JS WPSC_Purchase_Log_Action_Links.log_id to be a numeric ID.
Do purchase log actions on admin_init.
Purchase log action link AJAX should only show alert if there are error messages.
Purchase log action link AJAX should return success values of true, false or null by default.

Returning null displays no feedback. True and false display success or failure.