Updated emogrifier class to latest version from vanderlee: fixes...

...a few bugs, supports some additional selectors and appears to work well. See https://github.com/vanderlee/Emogrifier/blob/master/Emogrifier/Emogrifier.php

I have done only minor testing with a few HTML emails on one of our sites, but it appears to work great, and fixes a few selector precedence issues I was having.