Fixes for jQuery IE XHR error and test for existing subject and from to prevent Zend Mail Error

a) 
1.8.0 jQuery causes IE error on our product detail pages and prevents other scripts from running (thus preventing add to cart). 1.8.2 fixes XHR error.

b) 
if (!$mail->getSubject()) check before setting subject
if (!$mail->getFrom())  check before setting From
Zend Mail was failing preventing some system transactional emails from sending.