[CLEANUP] Use method getAllNodesWithStyleAttribute() everywhere (#433)
[CLEANUP] Use method getAllNodesWithStyleAttribute() everywhere (#433)

Updated method handleXPathError() to also catch eventual programming errors
in method getAllNodesWithStyleAttribute() and also replaced all instances of
$xPath->query('//*[@style]') with $this->getAllNodesWithStyleAttribute().

MyIntervals/emogrifier,jjriv/emogrifier